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Limits

Class 11th Mathematics RD Sharma Solution
Exercise 29.1
  1. Show that lim_ x arrow0 x/|x| does not exist.
  2. Find k so that lim_ x arrow2 f (x) may exist, where f (x) = 2x+3 , x less than…
  3. Show that lim_ x arrow0 1/x does not exist.
  4. Let f(x) be a function defined by f (x) = c 3x/|x|+2x , x not equal 0 0 , x = 0…
  5. Let f (x) = x+1 , x0 x-1 , x0 . Prove that lim_ x arrow0 f (x) does not exist.…
  6. Let f (x) = x+5 , x0 x-4 , x0 . Prove that lim_ x arrow0 f (x) does not exist.…
  7. Find lim_ x arrow3 f (x) , where f (x) = 4 , x3 x+1 , x3
  8. If f (x) = ll 2x+3 , & x less than equal to 0 3 (x+1) , x0 . Find lim_ x arrow0…
  9. Find lim_ x arrow1 f (x) , if f (x) = ll x^2 - 1 , x less than equal to 1 - x^2…
  10. Evaluate lim_ x arrow0 f (x) , where f (x) = ll |x|/x , x not equal 0 0 , x =…
  11. Let a1, a2, …….an be fixed real numbers such that f(x) = (x - a1) (x - a2)…
  12. Find lim_ x arrow1^+ 1/x-1
  13. lim_ x arrow2^+ x-3/x^2 - 4 Evaluate the following one - sided limits:…
  14. lim_ x arrow2^- x-3/x^2 - 4 Evaluate the following one - sided limits:…
  15. lim_ x arrow0^+ 1/3x Evaluate the following one - sided limits:
  16. lim_ x arrow-8^+ 2x/x+8 Evaluate the following one - sided limits:…
  17. lim_ x arrow0^+ 2/x^1/5 Evaluate the following one - sided limits:…
  18. lim_ x arrow pi^-/2 tanx Evaluate the following one - sided limits:…
  19. lim_ x arrow pi /2^+ secx Evaluate the following one - sided limits:…
  20. lim_ x arrow0^- x^2 - 3x+2/x^3 - 2x^2 Evaluate the following one - sided…
  21. lim_ x arrow-2^+ x^2 - 1/2x+4 Evaluate the following one - sided limits:…
  22. lim_ x arrow0^- (2-cotx) Evaluate the following one - sided limits:…
  23. (xi) lim_ x arrow0^- 1+cosecx Evaluate the following one - sided limits:…
  24. Show that lim_ x arrow0 e^-1/x does not exist.
  25. lim_ x arrow2 [x] Find:
  26. lim_ x arrow 5/2 [x] Find:
  27. lim_ x arrow1 [x] Find:
  28. Prove that lim_ x arrowa^+ [x] = [a] for all a ∈ R. Also, prove that lim_ x…
  29. Show that lim_ x arrow2^- x/[x] not equal lim_ x arrow2^+ x/[x] .…
  30. Find lim_ x arrow3^+ x/[x] . Is it equal to lim_ x arrow3^- x/[x] .…
  31. Find lim_ x arrow-5/2 [x] .
  32. Evaluate lim_ x arrow2 f (x) (if it exists), where f (x) = c x-[x] , x2 4 , x…
  33. Show that lim_ x arrow0 sin 1/x does not exist.
  34. Let f (x) = r kcosx/pi -2x , x not equal pi /2 3 , x not equal pi /2 and if…
Exercise 29.10
  1. lim_ x arrow0 5^x - 1/root 4+x-2 Evaluate the following limits:
  2. lim_ x arrow0 log (1+x)/3^x - 1 Evaluate the following limits:
  3. lim_ x arrow0 a^x + a^-x - 2/x^2 Evaluate the following limits:
  4. lim_ x arrow0 a^mx - 1/b^nx - 1 , n not equal 0 Evaluate the following limits:…
  5. lim_ x arrow0 a^x + b^x - 2/x Evaluate the following limits:
  6. lim_ x arrow0 9^x - 2.6^x + 4^x/x Evaluate the following limits:
  7. lim_ x arrow0 8^x - 4^x - 2^x + 1/x^2 Evaluate the following limits:…
  8. lim_ x arrow0 a^mx - b^nx/x Evaluate the following limits:
  9. lim_ x arrow0 a^x + b^x + c^x - 3/x Evaluate the following limits:…
  10. lim_ x arrow2 x-2/log_a (x-1) Evaluate the following limits:
  11. lim_ x arrow0 5^x + 3^x + 2^x - 3/x Evaluate the following limits:…
  12. lim_ x arrow infinity (a^1/x-1) x Evaluate the following limits:
  13. lim_ x arrow0 a^mx - b^nx/sinkx Evaluate the following limits:
  14. lim_ x arrow0 a^x + b^x - c^c - d^x/x Evaluate the following limits:…
  15. lim_ x arrow0 e^x - 1+sinx/x Evaluate the following limits:
  16. lim_ x arrow0 sin2x/e^x - 1 Evaluate the following limits:
  17. lim_ x arrow0 e^sinx-1/x Evaluate the following limits:
  18. lim_ x arrow0 e^2x - e^x/sin2x Evaluate the following limits:
  19. lim_ x arrowa logx-loga/x-a Evaluate the following limits:
  20. lim_ x arrow0 log (a+x) - log (a-x)/x Evaluate the following limits:…
  21. lim_ x arrow0 log (2+x) + log0.5/x Evaluate the following limits:…
  22. lim_ x arrow0 log (a+x) - loga/x Evaluate the following limits:
  23. lim_ x arrow0 log (3+x) - log (3-x)/x Evaluate the following limits:…
  24. lim_ x arrow0 8^x - 2^x/x Evaluate the following limits:
  25. lim_ x arrow0 x (2^x - 1)/1-cosx Evaluate the following limits:
  26. lim_ x arrow0 root 1+x-1/log (1+x) Evaluate the following limits:…
  27. lim_ x arrow0 log|1+x^3 |/sin^3x Evaluate the following limits:
  28. lim_ x arrow pi /2 a^cost-a^cosx/cotx-cosx Evaluate the following limits:…
  29. lim_ x arrow0 e^x - 1/root 1-cosx Evaluate the following limits:
  30. lim_ x arrow5 e^x - e^5/x-5 Evaluate the following limits:
  31. lim_ x arrow0 e^x+2 - e^2/x Evaluate the following limits:
  32. lim_ x arrow pi /2 e^cosx-1/cosx Evaluate the following limits:
  33. lim_ x arrow0 e^3+x - sinx-e^3/x Evaluate the following limits:
  34. lim_ x arrow0 e^x - x-1/2 Evaluate the following limits:
  35. lim_ x arrow0 e^3x - e^2x/x Evaluate the following limits:
  36. lim_ x arrow0 e^tanx-1/tanx Evaluate the following limits:
  37. lim_ x arrow0 e^6x - e^sinx/x-sinx Evaluate the following limits:…
  38. lim_ x arrow0 e^tanx-1/x Evaluate the following limits:
  39. lim_ x arrow0 e^x - e^sinx/x-sinx Evaluate the following limits:
  40. lim_ x arrow0 3^2+x - 9/x Evaluate the following limits:
  41. lim_ x arrow0 a^x - a^-x/x Evaluate the following limits:
  42. lim_ x arrow0 x (e^x - 1)/1-cosx Evaluate the following limits:
  43. lim_ x arrow pi /2 2^-cosx-1/x (x - pi /2) Evaluate the following limits:…
Exercise 29.11
  1. lim_ x arrow pi (1 - x/pi)^pi Evaluate the following limits:
  2. lim_ x arrow0^+ 1+tan^root x^1/2x Evaluate the following limits:
  3. lim_ x arrow0 (cosx)^1 / sinx Evaluate the following limits:
  4. lim_ x arrow0 (cosx+sinx)^1/x Evaluate the following limits:
  5. lim_ x arrow0 (cosx+asinx)^1/x Evaluate the following limits:
  6. lim_ x arrow infinity x^2 + 2x+3/2x^2 + x+5^3x-2/3x+2 Evaluate the following…
  7. lim_ x arrow1 x^3 + 2x^2 + x+1/x^2 + 2x+3^1-cos (x-1)/(x-1)^2 Evaluate the…
  8. lim_ x arrow0 e^x + e^-x - 2/x^2^1/x^2 Evaluate the following limits:…
  9. lim_ x arrowa sinx/sina^1/x-a Evaluate the following limits:
  10. lim_ x arrow infinity 3x^2 + 1/4x^2 - 1^x^3/1+x Evaluate the following limits:…
Exercise 29.2
  1. lim_ x arrow1 x^2 + 1/x+1 Evaluate the following limits:
  2. lim_ x arrow0 2x^2 + 3x+4/x^2 + 3x+2 Evaluate the following limits:…
  3. lim_ x arrow3 root 2x+3/x+3 Evaluate the following limits:
  4. lim_ x arrow1 root x+8/root x Evaluate the following limits:
  5. lim_ x arrowa root x + root a/x+a Evaluate the following limits:
  6. lim_ x arrow1 1 + (x-1)^2/1+x^2 Evaluate the following limits:
  7. lim_ x arrow0 x^2/3-9/x-27 Evaluate the following limits:
  8. lim_ x arrow0 9 Evaluate the following limits:
  9. lim_ x arrow2 (3-x) Evaluate the following limits:
  10. lim_ x arrow-1 (4x^2 + 2) Evaluate the following limits:
  11. lim_ x arrow-1 x^3 - 3x+1/x-1 Evaluate the following limits:
  12. lim_ x arrow0 3x+1/x+3 Evaluate the following limits:
  13. lim_ x arrow3 x^2 - 9/x+2 Evaluate the following limits:
  14. lim_ x arrow0 ax+b/cx+d , d not equal 0 Evaluate the following limits:…
Exercise 29.3
  1. lim_ x arrow-5 2x^2 + 9x-5/x+5 Evaluate the following limits:
  2. lim_ x arrow3 x^2 - 4x+3/x^2 - 2x-3 Evaluate the following limits:…
  3. lim_ x arrow3 x^4 - 81/x^2 - 9 Evaluate the following limits:
  4. Evaluate the following limits:
  5. lim_ x arrow-1/2 8x^3 + 1/2x+1 Evaluate the following limits:
  6. lim_ x arrow4 x^2 - 7x+12/x^2 - 3x-4 Evaluate the following limits:…
  7. lim_ x arrow2 x^4 - 16/x-2 Evaluate the following limits:
  8. lim_ x arrow5 x^2 - 9x+20/x^2 - 6x+5 Evaluate the following limits:…
  9. lim_ x arrow-1 x^3 + 1/x+1 Evaluate the following limits:
  10. lim_ x arrow5 x^3 - 125/x^2 - 7x+10 Evaluate the following limits:…
  11. lim_ x arrow root 2 x^2 - 2/x^2 + root 2x-4 Evaluate the following limits:…
  12. lim_ x arrow root 3 x^2 - 3/x^2 + 3 root 3x-12 Evaluate the following limits:…
  13. lim_ x arrow root 3 x^4 - 9/x^2 + 4 root 3x-15 Evaluate the following limits:…
  14. lim_ x arrow2 (x/x-2 - 4/x^2 - 2x) Evaluate the following limits:…
  15. lim_ x arrow1 (1/x^2 + x-2 - x/x^3 - 1) Evaluate the following limits:…
  16. lim_ x arrow3 (1/x-3 - 2/x^2 - 4x+3) Evaluate the following limits:…
  17. lim_ x arrow2 (1/x-2 - 2/x^2 - 2x) Evaluate the following limits:…
  18. lim_ x arrow1/4 4x-1/2 root x-1 Evaluate the following limits:
  19. lim_ x arrow4 x^2 - 16/root x-2 Evaluate the following limits:
  20. lim_ x arrow0 (a+x)^2 - a^2/x Evaluate the following limits:
  21. lim_ x arrow2 (1/x-2 - 4/x^3 - 2x^2) Evaluate the following limits:…
  22. lim_ x arrow3 (1/x-3 - 3/x^2 - 3x) Evaluate the following limits:…
  23. lim_ x arrow1 (1/x-1 - 2/x^2 - 1) Evaluate the following limits:
  24. lim_ x arrow3 (x^2 - 9) (1/x+3 + 1/x-3) Evaluate the following limits:…
  25. lim_ x arrow1 x^4 - 3x^3 + 2/x^3 - 5x^2 + 3x+1 Evaluate the following limits:…
  26. lim_ x arrow2 x^3 + 3x^2 - 9x-2/x^3 - x-6 Evaluate the following limits:…
  27. lim_ x arrow1 1-x^-1/3/1-x^-2/3 Evaluate the following limits:
  28. lim_ x arrow3 x^2 - x-6/x^3 - 3x^2 + x-3 Evaluate the following limits:…
  29. lim_ x arrow-2 x^3 + x^2 + 4x+12/x^3 - 3x+2 Evaluate the following limits:…
  30. lim_ x arrow1 x^3 + 3x^2 - 6x+2/x^3 + 3x^2 - 3x-1 Evaluate the following…
  31. lim_ x arrow2 1/x-2 - 2 (2x-3)/x^3 - 3x^2 + 2x Evaluate the following limits:…
  32. lim_ x arrow1 root x^2 - 1 + root x-1/root x^2 - 1 , x1 Evaluate the following…
  33. lim_ x arrow1 x-2/x^2 - x - 1/x^3 - 3x^2 + 2x Evaluate the following limits:…
  34. lim_ x arrow1 x^7 - 2x^5 + 1/x^3 - 3x^2 + 2 Evaluate the following limits:…
Exercise 29.4
  1. lim_ x arrow0 root 1+x+x^2 - 1/x Evaluate the following limits:
  2. lim_ x arrow0 2x/root a+x - root a-x Evaluate the following limits:…
  3. lim_ x arrow0 root a^2 + x^2 - a/x^2 Evaluate the following limits:…
  4. lim_ x arrow0 root 1+x - root 1-x/2x Evaluate the following limits:…
  5. lim_ x arrow2 root 3-x-1/2-x Evaluate the following limits:
  6. lim_ x arrow3 x-3/root x-2 - root 4-x Evaluate the following limits:…
  7. lim_ x arrow0 x-1/root x^2 + 3 - 2 Evaluate the following limits:…
  8. lim_ x arrow1 root 5x-4 - root x/x-1 Evaluate the following limits:…
  9. lim_ x arrow1 x-1/root x^2 + 3 - 2 Evaluate the following limits:…
  10. lim_ x arrow3 root x+3 - root 6/x^2 - 9 Evaluate the following limits:…
  11. lim_ x arrow1 root 5x-4 - root x/x^2 - 1 Evaluate the following limits:…
  12. lim_ x arrow0 root 1+x-1/x Evaluate the following limits:
  13. lim_ x arrow2 root x^2 + 1 - root 5/x-2 Evaluate the following limits:…
  14. lim_ x arrow2 x-2/root x - root 2 Evaluate the following limits:
  15. lim_ x arrow7 4 - root 9+x/1 - root 8-x Evaluate the following limits:…
  16. lim_ x arrow0 root a+x - root a/x root a^2 + ax Evaluate the following limits:…
  17. lim_ x arrow5 x-5/root 6x-5 - root 4x+5 Evaluate the following limits:…
  18. lim_ x arrow1 root 5x-4 - root x/x^3 - 1 Evaluate the following limits:…
  19. lim_ x arrow2 root 1+4x - root 5+2x/x-2 Evaluate the following limits:…
  20. lim_ x arrow1 root 3+x - root 5-x/x^2 - 1 Evaluate the following limits:…
  21. lim_ x arrow0 root 1+x^2 - root 1-x^2/x Evaluate the following limits:…
  22. lim_ x arrow0 root 1+x+x^2 - root x+1/2x^2 Evaluate the following limits:…
  23. lim_ x arrow4 2 - root x/4-x Evaluate the following limits:
  24. lim_ x arrowa x-a/root x - root a Evaluate the following limits:
  25. lim_ x arrow0 root 1+3x - root 1-3x/x Evaluate the following limits:…
  26. lim_ x arrow0 root 2-x - root 2+x/x Evaluate the following limits:…
  27. lim_ x arrow1 root 3+x - root 5-x/x^2 - 1 Evaluate the following limits:…
  28. lim_ x arrow1 (2x-3) (root x-1)/3x^2 + 3x-6 Evaluate the following limits:…
  29. lim_ x arrow0 root 1+x^2 - root 1+x/root 1+x^3 - root 1+x Evaluate the…
  30. lim_ x arrow1 x^2 - root x/root x-1 Evaluate the following limits:…
  31. lim_ h arrow0 root x+h - root x/h , x not equal 0 Evaluate the following…
  32. lim_ x arrow root 10 root 7+2x - (root 5 + root 2)/x^2 - 10 Evaluate the…
  33. lim_ x arrow root 6 root 5+2x - (root 3 + root 2)/x^2 - 6 Evaluate the…
  34. lim_ x arrow root 2 root 3+2x - (root 2+1)/x^2 - 2 Evaluate the following…
Exercise 29.5
  1. lim_ x arrowa (x+2)^5/2 - (a+2)^5/2/x-a Evaluate the following limits:…
  2. lim_ x arrowa (x+2)^3/2 - (a+2)^3/2/x-a Evaluate the following limits:…
  3. lim_ x arrowa (1+x)^6 - 1/(1+x)^2 - 1 Evaluate the following limits:…
  4. lim_ x arrowa x^2/7-a^2/7/x-a Evaluate the following limits:
  5. lim_ x arrowa x^5/7-a^5/7/x^2/7-a^2/7 Evaluate the following limits:…
  6. lim_ x arrow-1/2 8x^3 + 1/2x+1 Evaluate the following limits:
  7. lim_ x arrow27 (x^1/3+3) (x^1/3-3)/x-27 Evaluate the following limits:…
  8. lim_ x arrow4 x^3 - 64/x^2 - 16 Evaluate the following limits:
  9. lim_ x arrow1 x^15 - 1/x^10 - 1 Evaluate the following limits:
  10. lim_ x arrow-1 x^3 + 1/x+1 Evaluate the following limits:
  11. lim_ x arrow2 x^2/3-a^2/3/x^3/4-a^3/4 Evaluate the following limits:…
  12. If lim_ x arrow3 x^n - 3^n/x-3 = 108 , find the value of n.
  13. if lim_ x arrowa x^9 - a^9/x-a = 9 , find all possible values of a.…
  14. If lim_ x arrowa x^5 - a^5/x-a = 405 , find all possible values of a.…
  15. If lim_ x arrowa x^9 - a^9/x-a = lim_ x arrow5 (4+x) , find all possible…
  16. If lim_ x arrowa x^3 - a^3/x-a = lim_ x arrow1 x^4 - 1/x-1 , find all possible…
Exercise 29.6
  1. lim_ x arrow infinity (3x-1) (4x-2)/(x+8) (x-1) Evaluate the following limits:…
  2. lim_ x arrow infinity 3x^3 - 4x^2 + 6x-1/2x^3 + x^2 - 5x+7 Evaluate the…
  3. lim_ x arrow infinity 5x^3 - 6/root 9+4x^6 Evaluate the following limits:…
  4. lim_ x arrow infinity root x^2 + cx - x Evaluate the following limits:…
  5. lim_ x arrow infinity root x+1 - root x Evaluate the following limits:…
  6. lim_ x arrow infinity root x^2 + 7x - x Evaluate the following limits:…
  7. lim_ x arrow infinity x/root 4x^2 + 1 - 1 Evaluate the following limits:…
  8. lim_ n arrow infinity n^2/1+2+3 + l +n Evaluate the following limits:…
  9. lim_ x arrow infinity 3x^-1 + 4x^-2/5x^-1 + 6x^-2 Evaluate the following…
  10. lim_ x arrow infinity root x^2 + a^2 + root x^2 + b^2/root x^2 + c^2 + root…
  11. lim_ n arrow infinity (n+2) ! + (n+1) !/(n+2) ! - (n+1) ! Evaluate the…
  12. lim_ x arrow infinity x root x^2 + 1 - root x^2 - 1 Evaluate the following…
  13. lim_ x arrow infinity x root x+1 - root x root x+2 Evaluate the following…
  14. lim_ n arrow infinity 1^2 + 2^2 + l +n^2/n^3 Evaluate the following limits:…
  15. lim_ n arrow infinity (1/n^2 + 2/n^2 + 3/n^2 + l + n-1/n^2) Evaluate the…
  16. lim_ n arrow infinity 1^3 + 2^3 + l +n^3/n^4 Evaluate the following limits:…
  17. lim_ n arrow infinity 1^3 + 2^3 + l +n^3/(n-1)^4 Evaluate the following…
  18. lim_ x arrow infinity root x root x+1 - root x Evaluate the following limits:…
  19. lim_ n arrow infinity (1/3 + 1/3^2 + 1/3^3 + l + 1/3^n) Evaluate the following…
  20. lim_ x arrow infinity x^4 + 7x^3 + 46x+a/x^4 + 6 , where a is a non-zero real…
  21. f (x) = ax^2 + b/x^2 + 1 , lim_ x arrow0 f (x) = 1 and lim_ x arrow infinity f…
  22. Show that lim_ x arrow infinity (root x^2 + x+1 - x) not equal lim (root x^2 +…
  23. lim_ x arrow - infinity (root 4x^2 - 7x + 2x) Evaluate the following limits:…
  24. lim_ x arrow - infinity (root x^2 - 8x + x) Evaluate the following limits:…
  25. Evaluate: lim_ n arrow infinity 1^4 + 2^4 + 3^4 + l +n^4/n^3 - lim_ n arrow…
  26. Evaluate: lim_ n arrow infinity 1.2+2.3+3.4 + l +n (n+1)/n^3
Exercise 29.7
  1. lim_ x arrow0 sin3x/5x Evaluate the following limits:
  2. lim_ x arrow0 sinx^0/x Evaluate the following limits:
  3. lim_ x arrow0 x^2/sinx^2 Evaluate the following limits:
  4. lim_ x arrow0 sinxcosx/3x Evaluate the following limits:
  5. lim_ x arrow0 3sinx-4sin^3x/x Evaluate the following limits:
  6. lim_ x arrow0 tan8x/sin2x Evaluate the following limits:
  7. lim_ x arrow0 tanmx/tannx Evaluate the following limits:
  8. lim_ x arrow0 sin5x/tan3x Evaluate the following limits:
  9. lim_ x arrow0 sinx^0/x^0 Evaluate the following limits:
  10. lim_ x arrow0 7xcosx-3sinx/4x+tanx Evaluate the following limits:…
  11. lim_ x arrow0 cosax-cosbx/coscx-cosdx Evaluate the following limits:…
  12. lim_ x arrow0 tan^23x/x^2 Evaluate the following limits:
  13. lim_ x arrow0 1-cosmx/x^2 Evaluate the following limits:
  14. lim_ x arrow0 3sin2x+2x/3x+2tan3x Evaluate the following limits:
  15. lim_ x arrow0 cos3x-cos7x/x^2 Evaluate the following limits:
  16. lim_ theta arrow0 sin3theta /tan2theta Evaluate the following limits:…
  17. lim_ x arrow0 sinx^2 (1-cosx^2)/x^6 Evaluate the following limits:…
  18. lim_ x arrow0 sin^24x^2/x^4 Evaluate the following limits:
  19. lim_ x arrow0 xcosx+2sinx/x^2 + tanx Evaluate the following limits:…
  20. lim_ x arrow0 2x-sinx/tanx+x Evaluate the following limits:
  21. lim_ x arrow0 5xcosx+3sinx/3x^2 + tanx Evaluate the following limits:…
  22. lim_ x arrow0 sin3x-sinx/sinx Evaluate the following limits:
  23. lim_ x arrow0 sin5x-sin3x/sinx Evaluate the following limits:
  24. lim_ x arrow0 cos3x-cos5x/x^2 Evaluate the following limits:
  25. lim_ x arrow0 tan3x-2x/3x-sin^2x Evaluate the following limits:
  26. lim_ x arrow0 sin (2+x) - sin (2-x)/x Evaluate the following limits:…
  27. lim_ h arrow0 (a+h)^2sin (a+h) - a^2sina/h Evaluate the following limits:…
  28. lim_ x arrow0 tanx-sinx/sin3x-3sinx Evaluate the following limits:…
  29. lim_ x arrow0 sec5x-sec3x/sec3x-secx Evaluate the following limits:…
  30. lim_ x arrow0 1-cos2x/cos2x-cos8x Evaluate the following limits:
  31. lim_ x arrow0 1-cos2x+tan^2x/xsinx Evaluate the following limits:…
  32. lim_ x arrow0 sin (a+x) + sin (a-x) - 2sina/xsinx Evaluate the following…
  33. lim_ x arrow0 x^2 - tan2x/tanx Evaluate the following limits:
  34. lim_ x arrow0 root 2 - root 1+cosx/sin^2x Evaluate the following limits:…
  35. lim_ x arrow0 xtanx/1-cosx Evaluate the following limits:
  36. lim_ x arrow0 x^2 + 1-cosx/xsinx Evaluate the following limits:
  37. lim_ x arrow0 sin2x (cos3x-cosx)/x^3 Evaluate the following limits:…
  38. lim_ x arrow0 2sinx^0 - sin2x^0/x^3 Evaluate the following limits:…
  39. lim_ x arrow0 x^3cotx/1-cosx Evaluate the following limits:
  40. lim_ x arrow0 xtanx/1-cos2x Evaluate the following limits:
  41. lim_ x arrow0 sin (3+x) - sin (3-x)/x Evaluate the following limits:…
  42. lim_ x arrow0 cos2x-1/cosx-1 Evaluate the following limits:
  43. lim_ x arrow0 3sin^2x-2sinx^2/3x^2 Evaluate the following limits:…
  44. lim_ x arrow0 root 1+sinx - root 1-sinx/x Evaluate the following limits:…
  45. lim_ x arrow0 1-cos4x/x^2 Evaluate the following limits:
  46. lim_ x arrow0 xcosx+sinx/x^2 + tanx Evaluate the following limits:…
  47. lim_ x arrow0 1-cos2x/3tan^2x Evaluate the following limits:
  48. lim_ theta arrow0 1-cos4theta /1-cos6theta Evaluate the following limits:…
  49. lim_ x arrow0 ax+xcosx/bsinx Evaluate the following limits:
  50. lim_ theta arrow0 sin4theta /tan3theta Evaluate the following limits:…
  51. lim_ x arrow0 2sinx-sin2x/x^3 Evaluate the following limits:
  52. lim_ x arrow0 1-cos5x/1-cos6x Evaluate the following limits:
  53. lim_ x arrow0 cosecx-cotx/x Evaluate the following limits:
  54. lim_ x arrow0 sin3x+7x/4x+sin2x Evaluate the following limits:
  55. lim_ x arrow0 5x+4sin3x/4sin2x+7x Evaluate the following limits:
  56. lim_ x arrow0 3sinx-sin3x/x^3 Evaluate the following limits:
  57. lim_ x arrow0 tan2x-sin2x/x^3 Evaluate the following limits:
  58. lim_ x arrow0 sinax+bx/ax+sinbx Evaluate the following limits:
  59. lim_ x arrow0 (cosecx-cotx) Evaluate the following limits:
  60. lim_ x arrow0 (sin (alpha + beta) x+sin (alpha - beta) x+sin2alpha x/cos^2beta…
  61. lim_ x arrow0 cosax-cosbx/coscx-1 Evaluate the following limits:
  62. lim_ h arrow0 (a+h)^2sin (a+h) - a^2sina/h Evaluate the following limits:…
  63. If Evaluate the following limits:
Exercise 29.8
  1. lim_ x arrow pi /2 (pi /2 - x) tanx Evaluate the following limits:…
  2. lim_ x arrow pi /2 sin2x/cosx Evaluate the following limits:
  3. lim_ x arrow pi /2 cos^2x/1-sinx Evaluate the following limits:
  4. lim_ x arrow pi /3 root 1-cos6x/root 2 (pi /3-x) Evaluate the following limits:…
  5. lim_ x arrowa cosx-cosa/x-a Evaluate the following limits:
  6. lim_ x arrow pi /3 1-tanx/x - pi /4 Evaluate the following limits:…
  7. lim_ x arrow pi /2 1-sinx/(pi /2 - x)^2 Evaluate the following limits:…
  8. lim_ x arrow pi /3 root 3-tanx/pi -3x Evaluate the following limits:…
  9. lim_ x arrowa asinx-xsina/ax^2 - xa^2 Evaluate the following limits:…
  10. lim_ x arrow pi /2 root 2 - root 1+sinx/cos^2x Evaluate the following limits:…
  11. lim_ x arrow pi /2 root 2-sinx-1/(pi /2 - x)^2 Evaluate the following limits:…
  12. lim_ x arrow pi /4 root 2-cosx-sinx/(pi /4 - x)^2 Evaluate the following…
  13. lim_ x arrow pi /8 cot4x-cos4x/(pi -8x)^3 Evaluate the following limits:…
  14. lim_ x arrowa cosx-cosa/root x - root a Evaluate the following limits:…
  15. lim_ x arrow pi root 5+cosx-2/(pi -x)^2 Evaluate the following limits:…
  16. lim_ x arrowa cosroot x-cosroot a/x-a Evaluate the following limits:…
  17. lim_ x arrowa sinroot x-sinroot a/x-a Evaluate the following limits:…
  18. lim_ x arrow1 1-x^2/sin2pi x Evaluate the following limits:
  19. lim_ x arrow pi /4 f (x) - f (pi /4)/x - pi /4 , where f(x) = sin 2x Evaluate…
  20. lim_ x arrow1 1+cospi x/(1-x)^2 Evaluate the following limits:
  21. lim_ x arrow1 1-x^2/sinpi x Evaluate the following limits:
  22. lim_ x arrow pi /4 1-sin2x/1+cos4x Evaluate the following limits:…
  23. lim_ x arrow pi 1+cosx/tan^2x Evaluate the following limits:
  24. lim_ n arrow infinity nsin (pi /4n) cos (pi /4n) Evaluate the following…
  25. lim_ n arrow infinity 2^n-1sin (a/2^n) Evaluate the following limits:…
  26. lim_ n arrow infinity sin (a/2^n)/sin (b/2^n) Evaluate the following limits:…
  27. lim_ x arrow-1 x^2 - x-2/(x^2 + x) + sin (x+1) Evaluate the following limits:…
  28. lim_ x arrow2 x^2 - x-2/x^2 - 2x+sin (x-2) Evaluate the following limits:…
  29. lim_ x arrow1 (1-x) tan (pi x/2) Evaluate the following limits:
  30. lim_ x arrow pi /4 1-tanx/1 - root 2 sinx Evaluate the following limits:…
  31. lim_ x arrow pi root 2+cosx-1/(pi -x)^2 Evaluate the following limits:…
  32. lim_ x arrow pi /4 root cosx - root sinx/x - pi /4 Evaluate the following…
  33. lim_ x arrow1 1 - 1/x/sinpi (x-1) Evaluate the following limits:
  34. lim_ x arrow pi /6 cot^2x-3/cosecx-2 Evaluate the following limits:…
  35. lim_ x arrow pi /4 root 2-cosx-sinx/(4x - pi)^2 Evaluate the following limits:…
  36. lim_ x arrow pi /2 (pi /2 - x) sinx-2cosx/(pi /2 - x) + cotx Evaluate the…
  37. lim_ x arrow pi /4 cosx-sinx/(pi /4 - x) (cosx+sinx) Evaluate the following…
  38. lim_ x arrow pi 1-sin x/2/cos x/2 (cos x/4 - sin x/4) Evaluate the following…
Exercise 29.9
  1. lim_ x arrow pi 1+cosx/tan^2x Evaluate the following limits:
  2. lim_ x arrow pi /4 cosec^2x-2/cotx-1 Evaluate the following limits:…
  3. lim_ x arrow pi /6 cot^2x-3/cosecx-2 Evaluate the following limits:…
  4. lim_ x arrow pi /4 2-cosec^2x/1-cotx Evaluate the following limits:…
  5. lim_ x arrow pi root 2+cosx-1/(pi -x)^2 Evaluate the following limits:…
  6. lim_ x arrow 3 pi /2 1+cosec^2x/cot^2x Evaluate the following limits:…

Exercise 29.1
Question 1.

Show that does not exist.


Answer:

Given


f(x) =


f(x) =


To find


To limit to exist, we know …….(1)


Thus to find the limit using the concept ……(2)


……..(3)


……(4)


From above equations


(from 2)


Thus, limit does not exist.



Question 2.

Find k so that may exist, where .


Answer:

Given f(x) =


To find


To limit to exist, we know …….(1)


thus





From (1)



2(2 + 0) + 3 = (2 - 0) + k


4 + 3 = 2 + k


5 = k



Question 3.

Show that does not exist.


Answer:


To find


To limit to exist, we know …….(1)


Thus, to find the limit using the concept ……(2)


……..(3)


……(4)



From above equations



Thus, limit does not exist.



Question 4.

Let f(x) be a function defined by .

Show that does not exist.


Answer:

Given f(x) =


f(x) =


f(x) =


To find


To limit to exist we know …….(1)


Thus to find the limit using the concept ……(2)


……..(3)


……(4)



From above equations



Thus, limit does not exist.



Question 5.

Let . Prove that does not exist.


Answer:

Given f(x) =


To find whether exists?


To limit to exist we know …….(1)


Thus to limit to exist ……(2)




From above equations



Thus, the limit does not exists.



Question 6.

Let . Prove that does not exist.


Answer:

Given f(x) =


To find whether exists?


To limit to exist we know …….(1)


Thus to limit to exist ……(2)




From above equations



Thus, the limit does not exists.



Question 7.

Find , where



Answer:

Given f(x) =


To find


To limit to exist we know …….(1)


Thus to find the limit using the concept ……(2)


……..(3)


……(4)


From above equations



Thus from (2),(3) and (4)




Question 8.

If . Find and .


Answer:

Given f(x) =


(i)To find


To limit to exist, we know …….(1)


Thus to find the limit using the concept ……(2)


……..(3)


……(4)


…….(5)


From above equations


thus the limit exists


Thus from (5)



(ii) To find


To limit to exist, we know …….(1)


Thus to find the limit using the concept ……(2)


……..(3)


……(4)


From above equations



Thus from (2),(3) and (4)




Question 9.

Find , if .


Answer:

Given f(x) =


To find


To limit to exist we know …….(1)


Thus to find the limit using the concept ……(2)


……..(3)


……(4)


From above equations


thus the limit does not exists



Question 10.

Evaluate , where



Answer:

Given f(x) =


f(x) =


f(x) =


To find


To limit to exist we know …….(1)


Thus to find the limit using the concept ……(2)


……..(3)


……(4)



From above equations



Thus limit does not exists



Question 11.

Let a1, a2, …….an be fixed real numbers such that f(x) = (x – a1) (x – a2) …….(x – an)

What is ? For a ≠ a1, a2, …..,an compute


Answer:

Given: f(x) = (x – a1)(x – a2)…..(x – an)




Now,




Question 12.

Find


Answer:

Given f(x) =


To find




Question 13.

Evaluate the following one - sided limits:



Answer:

Given f(x) =


To find




Question 14.

Evaluate the following one - sided limits:



Answer:

Given f(x) =


To find




Question 15.

Evaluate the following one - sided limits:



Answer:

Given f(x) =


To find




Question 16.

Evaluate the following one - sided limits:



Answer:

Given f(x) =


Factorizing f(x)


f(x) =


f(x) =


f(x) =


To find




Question 17.

Evaluate the following one - sided limits:



Answer:

Given f(x) =


To find




Question 18.

Evaluate the following one - sided limits:



Answer:

Some standard limit are:




Thus to find:



= ∞



Question 19.

Evaluate the following one - sided limits:



Answer:

Some standard limit are:




Thus to find:



= - ∞



Question 20.

Evaluate the following one - sided limits:



Answer:

Given f(x) =


Factorizing f(x)


f(x) =


f(x) =


f(x) =


f(x) =


To find




Question 21.

Evaluate the following one - sided limits:



Answer:



Question 22.

Evaluate the following one - sided limits:



Answer:

Some standard limit are:




Thus to find:



= 2 + ∞ = ∞



Question 23.

Evaluate the following one - sided limits:

(xi)


Answer:

Some standard limit are:




Thus to find:



= 1 - ∞ = - ∞



Question 24.

Show that does not exist.


Answer:

Given f(x) =


To find


To limit to exist we know …….(1)


Thus to find the limit using the concept ……(2)


……..(3)


……(4)



From above equations



Thus, limit does not exist.



Question 25.

Find:



Answer:

We know greatest integer [x] is the integer part.


For f(x) = [x]


To find:



To limit to exist we know …….(1)


Thus to find the limit using the concept ……(2)


……..(3)


……(4)



From above equations



Thus, the limit does not exist.



Question 26.

Find:



Answer:

We know greatest integer [x] is the integer part.


For f(x) = [x]


To find:



To limit to exist we know …….(1)


Thus to find the limit using the concept ……(2)


……..(3)


……(4)



From above equations



Thus, limit does exists.



Question 27.

Find:



Answer:

We know greatest integer [x] is the integer part.


For f(x) = [x]


To find:



To limit to exist we know …….(1)


Thus to find the limit using the concept ……(2)


……..(3)


……(4)



From above equations



Thus limit does not exists.



Question 28.

Prove that for all a ∈ R. Also, prove that .


Answer:

To Prove:


L.H.S (Since, [a + h] = [a])


Hence, Proved.


Also,


To prove:


L.H.S (Since, [1 – h] = 0)


Hence, Proved.



Question 29.

Show that .


Answer:

We know greatest integer [x] is the integer part.


For f(x) = x/[x]


To show



Proof:


To limit to exist we know …….(1)


Thus to find the limit using the concept ……(2)


……..(3)


……(4)


From above equations




Question 30.

Find . Is it equal to .


Answer:

We know greatest integer [x] is the integer part.


For f(x) = x/[x]


To show



Proof:


To limit to exist we know …….(1)


Thus to find the limit using the concept ……(2)


……..(3)


……(4)


From above equations




Question 31.

Find .


Answer:

We know greatest integer [x] is the smallest integer nearest to that number .


For f(x) = [x]


To find:



To limit to exist we know …….(1)


Thus to find the limit using the concept ……(2)


……..(3)


……(4)



From above equations



Thus limit does exists



Question 32.

Evaluate (if it exists), where .


Answer:

Given f(x) =


To find


To limit to exist we know …….(1)


Thus to find the limit using the concept ……(2)


……..(3)


……(4)


…..(5)


From above equations



Thus the limit does not exist



Question 33.

Show that does not exist.


Answer:

To Prove: does not exist


Let us take the left-hand limit for the function:


L.H.L


Now, multiplying and dividing by h, we get,


L.H.L


Now, taking the right-hand limit of the function, we get,


R.H.L


Now, multiplying and dividing by h, we get,


R.H.L


Clearly, L.H.L ≠ R.H.L


Hence, limit does not exist.



Question 34.

Let and if , find the value of k.


Answer:


Let us find the limit of the function at .


Let


Therefore,


L.H.L


Now,


Hence, k = 6.




Exercise 29.10
Question 1.

Evaluate the following limits:



Answer:

As we need to find


We can directly find the limiting value of a function by putting the value of the variable at which the limiting value is asked if it does not take any indeterminate form (0/0 or ∞/∞ or ∞-∞, .. etc.)


Let Z = (indeterminate form)


∴ we need to take steps to remove this form so that we can get a finite value.


TIP: Most of the problems of logarithmic and exponential limits are solved using the formula and


Note: While modifying be careful that you don’t introduce any zero terms in the denominator


As Z


Multiplying both numerator and denominator by √(4+x)+2 so that we can remove the indeterminate form.


∴ Z


⇒ Z


{using a2 - b2 = (a + b)(a - b)}


⇒ Z


Using basic algebra of limits-


Z =


⇒ Z = 4


Use the formula:


∴ Z = 4log 5


Or,



Question 2.

Evaluate the following limits:



Answer:

As we need to find


We can directly find the limiting value of a function by putting the value of the variable at which the limiting value is asked if it does not take any indeterminate form (0/0 or ∞/∞ or ∞-∞, .. etc.)


Let


∴ we need to take steps to remove this form so that we can get a finite value.


TIP: Most of the problems of logarithmic and exponential limits are solved using the formula and


This question is a direct application of limits formula of exponential and logarithmic limits.


Use the formula: and


As Z =


To get the above forms, we need to divide numerator and denominator by x.


∴ Z {using basic limit algebra}


⇒ Z {using the formulae described above}


Hence,




Question 3.

Evaluate the following limits:



Answer:

As we need to find


We can directly find the limiting value of a function by putting the value of the variable at which the limiting value is asked if it does not take any indeterminate form (0/0 or ∞/∞ or ∞-∞, .. etc.)


Let Z


∴ we need to take steps to remove this form so that we can get a finite value.


TIP: Most of the problems of logarithmic and exponential limits are solved using the formula and


As Z =


∴ Z = {using (a+b)2 = a2+b2+2ab}


Using algebra of limit, we can write that


Z =


Use the formula:


∴ Z =


Hence,




Question 4.

Evaluate the following limits:



Answer:

As we need to find


We can directly find the limiting value of a function by putting the value of the variable at which the limiting value is asked if it does not take any indeterminate form (0/0 or ∞/∞ or ∞-∞, .. etc.)


Let Z


∴ we need to take steps to remove this form so that we can get a finite value.


TIP: Most of the problems of logarithmic and exponential limits are solved using the formula and


This question is a direct application of limits formula of exponential and logarithmic limits.


To get the desired forms, we need to include mx and nx as follows:


∴ Z


⇒ Z


Using algebra of limits-



Use the formula:


∴ Z =


Hence,




Question 5.

Evaluate the following limits:



Answer:

As we need to find


We can directly find the limiting value of a function by putting the value of the variable at which the limiting value is asked if it does not take any indeterminate form (0/0 or ∞/∞ or ∞-∞, .. etc.)


Let Z


∴ we need to take steps to remove this form so that we can get a finite value.


TIP: Most of the problems of logarithmic and exponential limits are solved using the formula and


This question is a direct application of limits formula of exponential and logarithmic limits.


To get similar forms as in a formula, we move as follows-


As Z


⇒ Z


Using algebra of limits we have-


Z


Use the formula:



Hence,




Question 6.

Evaluate the following limits:



Answer:

As we need to find


We can directly find the limiting value of a function by putting the value of the variable at which the limiting value is asked if it does not take any indeterminate form (0/0 or ∞/∞ or ∞-∞, .. etc.)


Let Z


∴ we need to take steps to remove this form so that we can get a finite value.


TIP: Most of the problems of logarithmic and exponential limits are solved using the formula and


As Z


∴ Z


{using (a-b)2 = a2+b2-2ab}


Z


To apply the formula we need to bring the exact form present in the formula, so-


Z


{Adding and subtracting 1 in numerator}


⇒ Z


Using algebra of limits-


Z


Use the formula:


∴ Z =


Hence,




Question 7.

Evaluate the following limits:



Answer:

As we need to find


We can directly find the limiting value of a function by putting the value of the variable at which the limiting value is asked if it does not take any indeterminate form (0/0 or ∞/∞ or ∞-∞, .. etc.)


Let Z


∴ we need to take steps to remove this form so that we can get a finite value.


TIP: Most of the problems of logarithmic and exponential limits are solved using the formula and


As Z


Using Algebra of limits-


We have-


Z


Use the formula:


∴ Z = log 4 × log 2


∵ log 4 = log 22 = 2log 2


{using properties of log}


∴ Z = 2(log 2)2


Hence,




Question 8.

Evaluate the following limits:



Answer:

As we need to find


We can directly find the limiting value of a function by putting the value of the variable at which the limiting value is asked if it does not take any indeterminate form (0/0 or ∞/∞ or ∞-∞, .. etc.)


Let Z


∴ we need to take steps to remove this form so that we can get a finite value.


TIP: Most of the problems of logarithmic and exponential limits are solved using the formula and


This question is a direct application of limits formula of exponential and logarithmic limits.


To get the desired forms, we need to include mx and nx as follows:


As Z


⇒ Z


{Adding and subtracting 1 in numerator}


⇒ Z


{using algebra of limits}


To get the form as present in the formula we multiply and divide m and n into both terms respectively:


∴ Z


Use the formula:


∴ Z = m log a – n log b


{using properties of log}


Hence,




Question 9.

Evaluate the following limits:



Answer:

As we need to find


We can directly find the limiting value of a function by putting the value of the variable at which the limiting value is asked if it does not take any indeterminate form (0/0 or ∞/∞ or ∞-∞, .. etc.)


Let Z


∴ we need to take steps to remove this form so that we can get a finite value.


TIP: Most of the problems of logarithmic and exponential limits are solved using the formula and


This question is a direct application of limits formula of exponential and logarithmic limits.


To get similar forms as in a formula, we move as follows-


As Z


⇒ Z


Using algebra of limits we have-


Z


Use the formula:



Hence,




Question 10.

Evaluate the following limits:



Answer:

As we need to find


We can directly find the limiting value of a function by putting the value of the variable at which the limiting value is asked if it does not take any indeterminate form (0/0 or ∞/∞ or ∞-∞, .. etc.)


Let Z


∴ We need to take steps to remove this form so that we can get a finite value.


TIP: Most of the problems of logarithmic and exponential limits are solved using the formula and


This question is a direct application of limits formula of exponential and logarithmic limits.


To get similar forms as in a formula, we move as follows-



As x→2 ∴ x-2 →0


Let x-2 = y


∴ Z =


We can’t use the formula directly as the base of log is we need to change this to e.


Applying the formula for change of base-


We have-


∴ Z =


Use the formula:


∴ Z =


Hence,




Question 11.

Evaluate the following limits:



Answer:

As we need to find


We can directly find the limiting value of a function by putting the value of the variable at which the limiting value is asked if it does not take any indeterminate form (0/0 or ∞/∞ or ∞-∞, .. etc.)


Let Z


∴ we need to take steps to remove this form so that we can get a finite value.


TIP: Most of the problems of logarithmic and exponential limits are solved using the formula and


This question is a direct application of limits formula of exponential and logarithmic limits.


To get similar forms as in formula, we move as follows-


As Z


⇒ Z


Using algebra of limits we have-


Z


Use the formula:



Hence,




Question 12.

Evaluate the following limits:



Answer:

As we need to find


We can directly find the limiting value of a function by putting the value of the variable at which the limiting value is asked if it does not take any indeterminate form (0/0 or ∞/∞ or ∞-∞, .. etc.)


Let Z


∴ We need to take steps to remove this form so that we can get a finite value.


TIP: Most of the problems of logarithmic and exponential limits are solved using the formula and


This question is a direct application of limits formula of exponential and logarithmic limits.


To get similar forms as in formula, we move as follows-


Let 1/x = y


As x→∞ ⇒ y→ 0


∴ Z can be rewritten as-


Z


Use the formula:


∴ Z =


Hence,




Question 13.

Evaluate the following limits:



Answer:

As we need to find


We can directly find the limiting value of a function by putting the value of the variable at which the limiting value is asked if it does not take any indeterminate form (0/0 or ∞/∞ or ∞-∞, .. etc.)


Let Z


∴ we need to take steps to remove this form so that we can get a finite value.


TIP: Most of the problems of logarithmic and exponential limits are solved using the formula and


This question is a direct application of limits formula of exponential and logarithmic limits and also use of sandwich theorem -


To get the desired forms, we need to include mx and nx as follows:


As Z


⇒ Z {Adding and subtracting 1 in numerator}


⇒ Z


{using algebra of limits}


To get the form as present in the formula we multiply and divide x into both terms respectively:


∴ Z


{manipulating to get the forms present in formulae}


Z


Use the formula: and


∴ Z


Hence,




Question 14.

Evaluate the following limits:



Answer:

As we need to find


We can directly find the limiting value of a function by putting the value of the variable at which the limiting value is asked if it does not take any indeterminate form (0/0 or ∞/∞ or ∞-∞, .. etc.)


Let Z =


∴ we need to take steps to remove this form so that we can get a finite value.


TIP: Most of the problems of logarithmic and exponential limits are solved using the formula and


This question is a direct application of limits formula of exponential and logarithmic limits.


To get similar forms as in a formula, we move as follows-


As Z =


⇒ Z =


Using algebra of limits we have-


Z =


Use the formula:



Hence,




Question 15.

Evaluate the following limits:



Answer:

As we need to find


We can directly find the limiting value of a function by putting the value of the variable at which the limiting value is asked if it does not take any indeterminate form (0/0 or ∞/∞ or ∞-∞, .. etc.)


Let Z


∴ We need to take steps to remove this form so that we can get a finite value.


TIP: Most of the problems of logarithmic and exponential limits are solved using the formula and


It also involves a trigonometric term, so there is a possibility of application of Sandwich theorem-


As Z


⇒ Z


Use the formula: and


∴ Z = log e + 1


{∵ log e = 1}


⇒ Z = 1+1 = 2


Hence,




Question 16.

Evaluate the following limits:



Answer:

As we need to find


We can directly find the limiting value of a function by putting the value of the variable at which the limiting value is asked if it does not take any indeterminate form (0/0 or ∞/∞ or ∞-∞, .. etc.)


Let Z


∴ We need to take steps to remove this form so that we can get a finite value.


TIP: Most of the problems of logarithmic and exponential limits are solved using the formula and


It also involves a trigonometric term, so there is a possibility of application of Sandwich theorem-


As Z


To get the desired form to apply the formula we need to divide numerator and denominator by x.


⇒ Z


Using algebra of limits, we have-


Z


Use the formula: and


∴ Z =


{∵ log e = 1}


⇒ Z = 2


Hence,




Question 17.

Evaluate the following limits:



Answer:

As we need to find


We can directly find the limiting value of a function by putting the value of the variable at which the limiting value is asked if it does not take any indeterminate form (0/0 or ∞/∞ or ∞-∞, .. etc.)


Let Z


∴ We need to take steps to remove this form so that we can get a finite value.


TIP: Most of the problems of logarithmic and exponential limits are solved using the formula and


It also involves a trigonometric term, so there is a possibility of application of Sandwich theorem-


As Z


To get rid of indeterminate form we will divide numerator and denominator by sin x


∴ Z


Using Algebra of limits we have-


Z


Where, A


and B


{from sandwich theorem}


As A


Let, sin x =y


As x→0 ⇒ y→0


∴ A


Using


A = log e = 1



Hence,




Question 18.

Evaluate the following limits:



Answer:

As we need to find


We can directly find the limiting value of a function by putting the value of the variable at which the limiting value is asked if it does not take any indeterminate form (0/0 or ∞/∞ or ∞-∞, .. etc.)


Let Z


∴ We need to take steps to remove this form so that we can get a finite value.


TIP: Most of the problems of logarithmic and exponential limits are solved using the formula and


It also involves a trigonometric term, so there is a possibility of application of Sandwich theorem-


As Z =


Adding and subtracting 1 in the numerator to get the desired form


⇒ Z =


⇒ Z =


{using algebra of limits}


To get the desired form to apply the formula we need to divide numerator and denominator by x.


⇒ Z


Using algebra of limits, we have-


Z


Use the formula: and


∴ Z =


{∵ log e = 1}


⇒ Z = 1/2


Hence,




Question 19.

Evaluate the following limits:



Answer:

As we need to find


We can directly find the limiting value of a function by putting the value of the variable at which the limiting value is asked if it does not take any indeterminate form (0/0 or ∞/∞ or ∞-∞, .. etc.)


Let Z


∴ We need to take steps to remove this form so that we can get a finite value.


TIP: Most of the problems of logarithmic and exponential limits are solved using the formula and


As Z


To apply the formula of logarithmic limits we need to get the form that matches with one in formula


∴ We proceed as follows-


Z


⇒ Z


⇒ Z


∵ x→a ⇒ x/a →1


⇒ x/a – 1 → 0


Let, (x/a)-1 = y


∴ y→0


Hence, Z can be rewritten as-


Z


Use the formula:


∴ Z


Hence,




Question 20.

Evaluate the following limits:



Answer:

As we need to find


We can directly find the limiting value of a function by putting the value of the variable at which the limiting value is asked if it does not take any indeterminate form (0/0 or ∞/∞ or ∞-∞, .. etc.)


Let Z =


∴ We need to take steps to remove this form so that we can get a finite value.


TIP: Most of the problems of logarithmic and exponential limits are solved using the formula and


As Z =


To apply the formula of logarithmic limits we need to get the form that matches with one in formula


∴ We proceed as follows-


Z =


⇒ Z =


⇒ Z =


To apply the formula of logarithmic limit we need denominator


∴ multiplying in numerator and denominator


Hence, Z can be rewritten as-


Z =


⇒ Z =


{Using algebra of limits}


⇒ Z =


As, x→0 ⇒


Let,


∴ Z =


Use the formula:


∴ Z =


Hence,




Question 21.

Evaluate the following limits:



Answer:

As we need to find


We can directly find the limiting value of a function by putting the value of the variable at which the limiting value is asked if it does not take any indeterminate form (0/0 or ∞/∞ or ∞-∞, .. etc.)


Let Z =


∴ We need to take steps to remove this form so that we can get a finite value.


TIP: Most of the problems of logarithmic and exponential limits are solved using the formula and


As Z =


To apply the formula of logarithmic limits we need to get the form that matches with one in formula


∴ We proceed as follows-


Z =


{using properties of log}


⇒ Z =


To apply the formula of logarithmic limit, we need the x/2 denominator


∴ multiplying 1/2 in numerator and denominator


Hence, Z can be rewritten as-


Z =


⇒ Z =


{Using algebra of limits}


As x→0 ⇒


Let,


∴ Z =


Use the formula:


∴ Z =


Hence,




Question 22.

Evaluate the following limits:



Answer:

As we need to find


We can directly find the limiting value of a function by putting the value of the variable at which the limiting value is asked if it does not take any indeterminate form (0/0 or ∞/∞ or ∞-∞, .. etc.)


Let Z =


∴ We need to take steps to remove this form so that we can get a finite value.


TIP: Most of the problems of logarithmic and exponential limits are solved using the formula and


As Z =


To apply the formula of logarithmic limits we need to get the form that matches with one in formula


∴ We proceed as follows-


Z = {using properties of log}


⇒ Z =


To apply the formula of logarithmic limit, we need x/a in the denominator


∴ multiplying 1/a in numerator and denominator


Hence, Z can be rewritten as-


Z =


⇒ Z =


{Using algebra of limits}


As x→0 ⇒


Let,


∴ Z =


Use the formula:


∴ Z =


Hence,




Question 23.

Evaluate the following limits:



Answer:

As we need to find


We can directly find the limiting value of a function by putting the value of the variable at which the limiting value is asked if it does not take any indeterminate form (0/0 or ∞/∞ or ∞-∞, .. etc.)


Let Z =


∴ We need to take steps to remove this form so that we can get a finite value.


TIP: Most of the problems of logarithmic and exponential limits are solved using the formula and


As Z =


To apply the formula of logarithmic limits we need to get the form that matches with one in formula


∴ We proceed as follows-


Z =


⇒ Z =


⇒ Z =


To apply the formula of logarithmic limit we need denominator


∴ multiplying in numerator and denominator


Hence, Z can be rewritten as-


Z =


⇒ Z =


{Using algebra of limits}


⇒ Z =


As, x→0 ⇒


Let,


∴ Z =


Use the formula:


∴ Z =


Hence,




Question 24.

Evaluate the following limits:



Answer:

As we need to find


We can directly find the limiting value of a function by putting the value of the variable at which the limiting value is asked if it does not take any indeterminate form (0/0 or ∞/∞ or ∞-∞, .. etc.)


Let Z =


∴ we need to take steps to remove this form so that we can get a finite value.


TIP: Most of the problems of logarithmic and exponential limits are solved using the formula and


This question is a direct application of limits formula of exponential and logarithmic limits.


As Z =


⇒ Z =


{Adding and subtracting 1 in numerator}


⇒ Z =


{using algebra of limits}


Use the formula:


∴ Z = log 8 – log 2 =


{using properties of log}


Hence,




Question 25.

Evaluate the following limits:



Answer:

As we need to find


We can directly find the limiting value of a function by putting the value of the variable at which the limiting value is asked if it does not take any indeterminate form (0/0 or ∞/∞ or ∞-∞, .. etc.)


Let Z =


∴ We need to take steps to remove this form so that we can get a finite value.


TIP: Most of the problems of logarithmic and exponential limits are solved using the formula and


It also involves a trigonometric term, so there is a possibility of application of Sandwich theorem-


As Z =


As, 1-cos x = 2sin2(x/2)


∴ Z =


⇒ Z =


To get the desired form to apply the formula we need to divide numerator and denominator by x2.


⇒ Z =


Using algebra of limits, we have-


Z =


Use the formula: and


∴ Z =


⇒ Z = 2 log 2


Hence,




Question 26.

Evaluate the following limits:



Answer:

As we need to find


We can directly find the limiting value of a function by putting the value of the variable at which the limiting value is asked if it does not take any indeterminate form (0/0 or ∞/∞ or ∞-∞, .. etc.)


Let Z =


∴ We need to take steps to remove this form so that we can get a finite value.


TIP: Most of the problems of logarithmic and exponential limits are solved using the formula and


As Z =


To apply the formula of logarithmic limits we need to get the form that matches with one in formula


∴ multiplying numerator and denominator by


⇒ Z =


⇒ Z =


{using (a+b)(a-b)=a2-b2}


⇒ Z =


⇒ Z =


Use the formula:


∴ Z = 1/2


Hence,




Question 27.

Evaluate the following limits:



Answer:

As we need to find


We can directly find the limiting value of a function by putting the value of the variable at which the limiting value is asked if it does not take any indeterminate form (0/0 or ∞/∞ or ∞-∞, .. etc.)


Let Z =


∴ We need to take steps to remove this form so that we can get a finite value.


TIP: Most of the problems of logarithmic and exponential limits are solved using the formula and


It also involves a trigonometric term, so there is a possibility of application of Sandwich theorem-


As Z =


To apply the formula of logarithmic limits we need to get the form that matches with one in formula


∴ dividing numerator and denominator by x3


⇒ Z =


⇒ Z =


⇒ Z =


{using algebra of limits}


Use the formula: and


∴ Z = 1/1


Hence,




Question 28.

Evaluate the following limits:



Answer:

As we need to find


We can directly find the limiting value of a function by putting the value of the variable at which the limiting value is asked if it does not take any indeterminate form (0/0 or ∞/∞ or ∞-∞, .. etc.)


Let Z =


∴ we need to take steps to remove this form so that we can get a finite value.


TIP: Most of the problems of logarithmic and exponential limits are solved using the formula and


This question is a direct application of limits formula of exponential limits.


As Z =


⇒ Z =


⇒ Z =


{using properties of exponents}


⇒ Z =


{using algebra of limits}


⇒ Z =


∴ Z =


As, x→ (π/2)


∴ cot(π/2) – cos(π/2) → 0


Let, y = cot x – cos x


∴ if x→π/2 ⇒ y→0


Hence, Z can be rewritten as-


Z =


Use the formula:


∴ Z = log a


Hence,




Question 29.

Evaluate the following limits:



Answer:

As we need to find


We can directly find the limiting value of a function by putting the value of the variable at which the limiting value is asked if it does not take any indeterminate form (0/0 or ∞/∞ or ∞-∞, .. etc.)


Let Z =


∴ We need to take steps to remove this form so that we can get a finite value.


TIP: Most of the problems of logarithmic and exponential limits are solved using the formula and


It also involves a trigonometric term, so there is a possibility of application of Sandwich theorem-


As Z =


To apply the formula we need to get the form as present in the formula. So we proceed as follows-


∵ Z =


Multiplying numerator and denominator by √(1+cos x)


⇒ Z =


Using (a+b)(a-b) = a2-b2


Z =


∵ √(1-cos2x) = sin x


⇒ Z =


{using algebra of limits}


⇒ Z =


Dividing numerator and denominator by x-


Z =


⇒ Z =


Use the formula: and


∴ Z =


{∵ log e = 1}


Hence,




Question 30.

Evaluate the following limits:



Answer:

As we need to find


We can directly find the limiting value of a function by putting the value of the variable at which the limiting value is asked if it does not take any indeterminate form (0/0 or ∞/∞ or ∞-∞, .. etc.)


Let Z =


∴ we need to take steps to remove this form so that we can get a finite value.


TIP: Most of the problems of logarithmic and exponential limits are solved using the formula and


This question is a direct application of limits formula of exponential limits.


As Z =


⇒ Z =


⇒ Z =


{using properties of exponents}


⇒ Z =


{using algebra of limits}


As, x→ 5


∴ x-5→ 0


Let, y = x-5


∴ if x→5 ⇒ y→0


Hence, Z can be rewritten as-


Z =


Use the formula:


∴ Z = e5 log e


{∵ log e = 1}


Hence,




Question 31.

Evaluate the following limits:



Answer:

As we need to find


We can directly find the limiting value of a function by putting the value of the variable at which the limiting value is asked if it does not take any indeterminate form (0/0 or ∞/∞ or ∞-∞, .. etc.)


Let Z =


∴ we need to take steps to remove this form so that we can get a finite value.


TIP: Most of the problems of logarithmic and exponential limits are solved using the formula and


This question is a direct application of limits formula of exponential limits.


As Z =


⇒ Z =


⇒ Z =


{using algebra of limits}


Use the formula:


∴ Z = e2 log e


{∵ log e = 1}


Hence,




Question 32.

Evaluate the following limits:



Answer:

As we need to find


We can directly find the limiting value of a function by putting the value of the variable at which the limiting value is asked if it does not take any indeterminate form (0/0 or ∞/∞ or ∞-∞, .. etc.)


Let Z =


∴ we need to take steps to remove this form so that we can get a finite value.


TIP: Most of the problems of logarithmic and exponential limits are solved using the formula and


This question is a direct application of limits formula of exponential limits.


As x→ π/2


∴ cos x → 0


Let, y = cos x


∴ if x→ π/2 ⇒ y→0


Hence, Z can be rewritten as-



Use the formula:


∴ Z = 1


{∵ log e = 1}


Hence,




Question 33.

Evaluate the following limits:



Answer:

As we need to find


We can directly find the limiting value of a function by putting the value of the variable at which the limiting value is asked if it does not take any indeterminate form (0/0 or ∞/∞ or ∞-∞, .. etc.)


Let Z = =


∴ we need to take steps to remove this form so that we can get a finite value.


TIP: Most of the problems of logarithmic and exponential limits are solved using the formula and


This question is a direct application of limits formula of exponential limits.


As Z =


⇒ Z =


⇒ Z =


{using algebra of limits}


Use the formula: and


∴ Z = e3 log e – 1 {∵ log e = 1}


Hence,




Question 34.

Evaluate the following limits:



Answer:

As we need to find


We can directly find the limiting value of a function by putting the value of the variable at which the limiting value is asked if it does not take any indeterminate form (0/0 or ∞/∞ or ∞-∞, .. etc.)


Let Z = =


As we got a finite value, so no need to do any modifications.


Hence,




Question 35.

Evaluate the following limits:



Answer:

As we need to find


We can directly find the limiting value of a function by putting the value of the variable at which the limiting value is asked if it does not take any indeterminate form (0/0 or ∞/∞ or ∞-∞, .. etc.)


Let Z =


∴ we need to take steps to remove this form so that we can get a finite value.


TIP: Most of the problems of logarithmic and exponential limits are solved using the formula and


This question is a direct application of limits formula of exponential and logarithmic limits.


As Z =


⇒ Z =


{Adding and subtracting 1 in numerator}


⇒ Z =


{using algebra of limits}


To get the form as present in the formula we multiply and divide 3 and 2 into both terms respectively:


⇒ Z =


Use the formula:


∴ Z = 3log e – 2log e= 3-2 = 1


{using log e = 1}


Hence,




Question 36.

Evaluate the following limits:



Answer:

As we need to find


We can directly find the limiting value of a function by putting the value of the variable at which the limiting value is asked if it does not take any indeterminate form (0/0 or ∞/∞ or ∞-∞, .. etc.)


Let Z = =


∴ we need to take steps to remove this form so that we can get a finite value.


TIP: Most of the problems of logarithmic and exponential limits are solved using the formula and


This question is a direct application of limits formula of exponential limits.


As, x→ 0


∴ tan x → 0


Let, y = tan x


∴ if x→ 0 ⇒ y→0


Hence, Z can be rewritten as-



Use the formula:


∴ Z = log e = 1


{∵ log e = 1}


Hence,




Question 37.

Evaluate the following limits:



Answer:

As we need to find


We can directly find the limiting value of a function by putting the value of variable at which the limiting value is asked, if it does not take any indeterminate form (0/0 or ∞/∞ or ∞-∞, .. etc)


Let Z = =


∴ we need to take steps to remove this form so that we can get a finite value.


TIP: Most of the problems of logarithmic and exponential limits are solved using the formula and


This question is a direct application of limits formula of exponential limits.


As Z =


⇒ Z =


⇒ Z =


{using properties of exponents}


⇒ Z =


{using algebra of limits}


⇒ Z =


∴ Z =


As, x→ 0


∴ bx-sin x → 0


Let, y = bx-sin x


∴ if x→0 ⇒ y→0


Hence, Z can be rewritten as-


Z =


Use the formula:


∴ Z = log e =1


{∵ log e = 1}


Hence,




Question 38.

Evaluate the following limits:



Answer:

As we need to find


We can directly find the limiting value of a function by putting the value of the variable at which the limiting value is asked if it does not take any indeterminate form (0/0 or ∞/∞ or ∞-∞, .. etc.)


Let Z = =


∴ we need to take steps to remove this form so that we can get a finite value.


TIP: Most of the problems of logarithmic and exponential limits are solved using the formula and


This question is a direct application of limits formula of exponential limits.


∵ Z =


To get the desired form, we proceed as follows-


Dividing numerator and denominator by tan x-


⇒ Z =


Using algebra of limits-


Z =


Use the formula - (sandwich theorem)


∴ Z =


As, x→ 0


∴ tan x → 0


Let, y = tan x


∴ if x→ 0 ⇒ y→0


Hence, Z can be rewritten as-



Use the formula:


∴ Z = log e = 1


{∵ log e = 1}


Hence,




Question 39.

Evaluate the following limits:



Answer:

As we need to find


We can directly find the limiting value of a function by putting the value of the variable at which the limiting value is asked if it does not take any indeterminate form (0/0 or ∞/∞ or ∞-∞, .. etc.)


Let Z = =


∴ we need to take steps to remove this form so that we can get a finite value.


TIP: Most of the problems of logarithmic and exponential limits are solved using the formula and


This question is a direct application of limits formula of exponential limits.


As Z =


⇒ Z =


⇒ Z =


{using properties of exponents}


⇒ Z =


{using algebra of limits}


⇒ Z =


∴ Z =


As, x→ 0


∴ x-sin x → 0


Let, y = x-sin x


∴ if x→0 ⇒ y→0


Hence, Z can be rewritten as-


Z =


Use the formula:


∴ Z = log e =1


{∵ log e = 1}


Hence,




Question 40.

Evaluate the following limits:



Answer:

As we need to find


We can directly find the limiting value of a function by putting the value of the variable at which the limiting value is asked if it does not take any indeterminate form (0/0 or ∞/∞ or ∞-∞, .. etc.)


Let Z = =


∴ we need to take steps to remove this form so that we can get a finite value.


TIP: Most of the problems of logarithmic and exponential limits are solved using the formula and


This question is a direct application of limits formula of exponential limits.


As Z =


⇒ Z =


⇒ Z =


{using algebra of limits}


Use the formula:


∴ Z = 9 log 3


Hence,




Question 41.

Evaluate the following limits:



Answer:

As we need to find


We can directly find the limiting value of a function by putting the value of the variable at which the limiting value is asked if it does not take any indeterminate form (0/0 or ∞/∞ or ∞-∞, .. etc.)


Let Z =


∴ we need to take steps to remove this form so that we can get a finite value.


TIP: Most of the problems of logarithmic and exponential limits are solved using the formula and


This question is a direct application of limits formula of exponential and logarithmic limits.


To get the desired forms, we need to include mx and nx as follows:


As Z =


⇒ Z =


{using law of exponents}


⇒ Z =


{using algebra of limits}


⇒ Z =


⇒ Z =


To get the form as present in the formula we multiply and divide by 2


∴ Z =


Use the formula:


∴ Z = 2 log a


Hence,




Question 42.

Evaluate the following limits:



Answer:

As we need to find


We can directly find the limiting value of a function by putting the value of the variable at which the limiting value is asked if it does not take any indeterminate form (0/0 or ∞/∞ or ∞-∞, .. etc)


Let Z =


∴ We need to take steps to remove this form so that we can get a finite value.


TIP: Most of the problems of logarithmic and exponential limits are solved using the formula and


It also involves a trigonometric term, so there is a possibility of application of Sandwich theorem-


As Z =


As, 1-cos x = 2sin2(x/2)


∴ Z =


⇒ Z =


To get the desired form to apply the formula we need to divide numerator and denominator by x2.


⇒ Z =


Using algebra of limits, we have-


Z =


Use the formula: and


∴ Z =


⇒ Z = 2 log e = 2


Hence,




Question 43.

Evaluate the following limits:



Answer:

As we need to find


We can directly find the limiting value of a function by putting the value of the variable at which the limiting value is asked if it does not take any indeterminate form (0/0 or ∞/∞ or ∞-∞, .. etc.)


Let Z = =


∴ we need to take steps to remove this form so that we can get a finite value.


TIP: Most of the problems of logarithmic and exponential limits are solved using the formula and


As Z =


⇒ Z = {using algebra of limits}


⇒ Z =


⇒ Z = {∵ sin(x-π/2) = -cos x}


As x→π/2


∴ x-π/2→0


Let x-π/2 = y and y→0


Z can be rewritten as-


Z =


Dividing numerator and denominator by sin y to get the form present in the formula


Z =


Using algebra of limits:


Z =


Use the formula: and


∴ Z =


Hence,





Exercise 29.11
Question 1.

Evaluate the following limits:



Answer:

As we need to find


We can directly find the limiting value of a function by putting the value of the variable at which the limiting value is asked if it does not take any indeterminate form (0/0 or ∞/∞ or ∞-∞,0 .. etc.)


Let Z =


As it is not taking any indeterminate form.


∴ Z = 0


Hence,




Question 2.

Evaluate the following limits:



Answer:

As we need to find


We can directly find the limiting value of a function by putting the value of the variable at which the limiting value is asked if it does not take any indeterminate form (0/0 or ∞/∞ or ∞-∞,1 .. etc.)


Let Z =


As it is taking indeterminate form.


∴ we need to take steps to remove this form so that we can get a finite value.


As, Z =


⇒ Z =


Taking log both sides-


⇒ log Z =


⇒ log Z =


{∵ log am = m log a}


Now it gives us a form that can be reduced to


Dividing numerator and denominator by tan2√x –


log Z =


using algebra of limits –




Let, tan2√x = y


As x→0+⇒ y→0+


∴ A =


Use the formula -


∴ A = 1


Now, B =


⇒ B =


Use the formula -


∴ B = 2


Hence,


log Z =


⇒ loge Z = 1/2


∴ Z = e1/2


Hence,




Question 3.

Evaluate the following limits:



Answer:

As we need to find


We can directly find the limiting value of a function by putting the value of the variable at which the limiting value is asked if it does not take any indeterminate form (0/0 or ∞/∞ or ∞-∞,1 .. etc.)


Let Z =


As it is taking indeterminate form-


∴ we need to take steps to remove this form so that we can get a finite value.


As, Z =


⇒ Z =


Taking log both sides-


⇒ log Z =


⇒ log Z =


{∵ log am = m log a}


Now it gives us a form that can be reduced to


log Z = {adding and subtracting 1 to cos x to get the form}


Dividing numerator and denominator by cos x – 1 to match with form in formula


∴ log Z =


using algebra of limits –


log Z =


∴ A =


Let, cos x - 1 = y


As x→0 ⇒ y→0


∴ A =


Use the formula -


∴ A = 1


Now, B =


∵ cos x – 1 = -2sin2(x/2) and sinx = 2sin(x/2)cos(x/2)


⇒ B =


∴ B = -cot 0 = ∞


∴ B = ∞


Hence,


log Z =


⇒ loge Z = 0


∴ Z = e0 = 1


Hence,




Question 4.

Evaluate the following limits:



Answer:

As we need to find


We can directly find the limiting value of a function by putting the value of the variable at which the limiting value is asked if it does not take any indeterminate form (0/0 or ∞/∞ or ∞-∞,1 .. etc.)


Let Z =


As it is taking indeterminate form-


∴ we need to take steps to remove this form so that we can get a finite value.


As, Z =


⇒ Z =


Taking log both sides-


⇒ log Z =


⇒ log Z =


{∵ log am = m log a}


Now it gives us a form that can be reduced to


log Z =


{adding and subtracting 1 to cos x to get the form}


Dividing numerator and denominator by cos x + sin x– 1 to match with form in formula


∴ log Z =


using algebra of limits –


log Z =


∴ A =


Let, cos x + sin x - 1 = y


As x→0 ⇒ y→0


∴ A =


Use the formula -


∴ A = 1


Now, B =


∵ cos x – 1 = -2sin2(x/2) and sin x = 2sin(x/2)cos(x/2)


⇒ B =


⇒ B =


⇒ B =


Use the formula -


⇒ B =


∴ B = 1


Hence,


log Z =


⇒ loge Z = 1


∴ Z = e1 = e


Hence,




Question 5.

Evaluate the following limits:



Answer:

As we need to find


We can directly find the limiting value of a function by putting the value of the variable at which the limiting value is asked if it does not take any indeterminate form (0/0 or ∞/∞ or ∞-∞,1 .. etc.)


Let Z =


As it is taking indeterminate form-


∴ we need to take steps to remove this form so that we can get a finite value.


As, Z =


⇒ Z =


Taking log both sides-


⇒ log Z =


⇒ log Z =


{∵ log am = m log a}


Now it gives us a form that can be reduced to


Adding and subtracting 1 to cos x to get the form-


log Z =


Dividing numerator and denominator by cos x + a sin x– 1 to match with form in formula


∴ log Z =


using algebra of limits –


log Z =


∴ A =


Let, cos x + asin x - 1 = y


As x→0 ⇒ y→0


∴ A =


Use the formula -


∴ A = 1


Now, B =


∵ cos x – 1 = -2sin2(x/2) and sin x = 2sin(x/2)cos(x/2)


⇒ B =


⇒ B =


⇒ B =


Use the formula -


⇒ B =


∴ B = 1/a


Hence,


log Z =


⇒ loge Z = a


∴ Z = ea = ea


Hence,




Question 6.

Evaluate the following limits:



Answer:

As we need to find


We can directly find the limiting value of a function by putting the value of the variable at which the limiting value is asked if it does not take any indeterminate form (0/0 or ∞/∞ or ∞-∞,1 .. etc.)


Let Z =


As it is taking indeterminate form-


∴ we need to take steps to remove this form so that we can get a finite value.


Z =


Take the log to bring the term in the product so that we can solve it more easily.


Taking log both sides-


log Z =


⇒ log Z =


{∵ log am = m log a}


⇒ log Z =


{using algebra of limits}


Still, if we put x = ∞ we get an indeterminate form,


Take the highest power of x common and try to bring x in the denominator of a term so that if we put x = ∞ term reduces to 0.


∴ log Z =


⇒ log Z =


⇒ log Z =


⇒ log Z =


∴ Loge Z =


⇒ Z = 1/2


Hence,




Question 7.

Evaluate the following limits:



Answer:

As we need to find


We can directly find the limiting value of a function by putting the value of the variable at which the limiting value is asked if it does not take any indeterminate form (0/0 or ∞/∞ or ∞-∞,1 .. etc.)


Let Z =


As it is taking indeterminate form-


∴ we need to take steps to remove this form so that we can get a finite value.


Z =


Take the log to bring the power term in the product so that we can solve it more easily.


Taking log both sides-


log Z =


⇒ log Z =


{∵ log am = m log a}


using algebra of limits-


⇒ log Z =


⇒ log Z =


⇒ log Z =


As, 1-cos x = 2sin2(x/2)


∴ log Z =


Let (x-1)/2 = y


As x→1 ⇒ y→0


∴ Z can be rewritten as


Log Z =


⇒ log Z =


Use the formula -


∴ log Z =


⇒ log Z =


∴ Z =


Hence,




Question 8.

Evaluate the following limits:



Answer:

Let


Putting the limit, we get,



This is an indeterminate form, so we need to solve this limit. Taking log on both sides we get,




Now, applying L-Hospital’s rule, we get,



Applying L-hospital rule again we get,





Question 9.

Evaluate the following limits:



Answer:

As we need to find


We can directly find the limiting value of a function by putting the value of the variable at which the limiting value is asked if it does not take any indeterminate form (0/0 or ∞/∞ or ∞-∞,1 .. etc.)


Let Z =


As it is taking indeterminate form-


∴ we need to take steps to remove this form so that we can get a finite value.


Z =


Take the log to bring the power term in the product so that we can solve it more easily.


Taking log both sides-


log Z =


{∵ log am = m log a}


Now it gives us a form that can be reduced to


⇒ log Z =


Dividing numerator and denominator by to get the desired form and using algebra of limits we have-


log Z =


if we assume then as x→a ⇒ y→ 0


⇒ log Z =


Use the formula-


∴ log Z =


⇒ log Z =


Now it gives us a form that can be reduced to


Try to use it. We are basically proceeding with a hit and trial attempt.


⇒ log Z =


∵ sin (A+B) = sin A cos B + cos A sin B


⇒ log Z =


⇒ log Z=


⇒ log Z =


⇒ log Z =


Use the formula-


⇒ log Z = cot a – 0


∴ log Z = cot a


∴ Z = ecot a


Hence,




Question 10.

Evaluate the following limits:



Answer:

As we need to find


We can directly find the limiting value of a function by putting the value of the variable at which the limiting value is asked if it does not take any indeterminate form (0/0 or ∞/∞ or ∞-∞,1 .. etc.)


Let Z =


As it is taking indeterminate form-


∴ we need to take steps to remove this form so that we can get a finite value.


Z =


Take the log to bring the term in the product so that we can solve it more easily.


Taking log both sides-


log Z =


⇒ log Z =


{∵ log am = m log a}


⇒ log Z =


{using algebra of limits}


Still, if we put x = ∞ we get an indeterminate form,


Take highest power of x common and try to bring x in denominator of a term so that if we put x = ∞ term reduces to 0.


∴ log Z =


⇒ log Z =


⇒ log Z =


⇒ log Z =


{∵ log (3/4) is a negative value as 3/4<1}


∴ Loge Z = -∞


⇒ Z = e-∞ = 0


Hence,





Exercise 29.2
Question 1.

Evaluate the following limits:



Answer:

Given limit

Putting the value of limits directly, i.e., x = 1, we have





Hence the value of the given limit is 1.




Question 2.

Evaluate the following limits:



Answer:

Given limit

Putting the value of limits directly, i.e. x = 0, we have





Hence the value of the given limit is 2.



Question 3.

Evaluate the following limits:



Answer:

Given limit

Putting the value of limits directly, i.e. x = 0, we have






Hence the value of the given limit is 0.5



Question 4.

Evaluate the following limits:



Answer:

Given limit

Putting the values of limits directly, i.e. x = 1, we have





Hence the value of the given limit is 3.



Question 5.

Evaluate the following limits:



Answer:

Given limit

Putting the values of limit directly, i.e. x = a, we have





Hence the value of the given limit is



Question 6.

Evaluate the following limits:



Answer:

Given limit

Putting the values of limits directly, i.e. x = 1, we have




Hence the value of the given limit is 0.5



Question 7.

Evaluate the following limits:



Answer:

Given limit

Putting the value of limit directly, i.e. x = 0, we have





Hence the value of the given limit is



Question 8.

Evaluate the following limits:



Answer:

Given the limit

Always remember the limiting value of a constant (such as 4, 13, b, etc.) is the constant itself.


So, the limiting value of constant 9 is itself, i.e., 9.



Question 9.

Evaluate the following limits:



Answer:

Given the limit

Putting the limiting value directly, i.e. x = 2, we have




Hence the value of the given limit is 1.



Question 10.

Evaluate the following limits:



Answer:

Given limit

Putting the value of limits directly, we have





Hence the value of the given limit is 6.



Question 11.

Evaluate the following limits:



Answer:

Given the limit

Putting the value of limits directly, i.e. x = -1, we have





Hence the value of the given limit is



Question 12.

Evaluate the following limits:



Answer:

Given limit

Putting the value of limit directly, i.e. x = 0, we have




Hence the value of the given limit is



Question 13.

Evaluate the following limits:



Answer:

Given limit

Putting the value of limits directly, i.e. x = 3, we have





Hence the value of the given limit is 0.



Question 14.

Evaluate the following limits:



Answer:

Given limit

Putting the value of limits directly, i.e. x = 0, we have




The given condition d ≠ 0 is reasonable because the denominator cannot be zero.


Hence the value of the given limit is .




Exercise 29.3
Question 1.

Evaluate the following limits:



Answer:



Since the form is indeterminant



Method 1: factorization







= 2(-5)-1


= -11


Method 2: By L hospital rule:


Differentiating numerator and denominator separately:




= 4(-5) + 9


= -11



Question 2.

Evaluate the following limits:



Answer:



Since the form is indeterminant



Method 1: factorization









Method 2: By L hospital rule:


Differentiating numerator and denominator separately:







Question 3.

Evaluate the following limits:



Answer:



Since the form is indeterminant



Method 1: factorization





Since a2-b2 = (a + b)(a-b)


Thus




= 32 + 32


= 18


Method 2:


By L hospital rule:


Differentiating numerator and denominator separately:





= 54



Question 4.

Evaluate the following limits:



Answer:



Since the form is indeterminant



Method 1: factorization





Since a3-b3 = (a-b)(a2 + b2 + ab) & a2-b2 = (a + b)(a-b)





= 3


Method 2: By L hospital rule:


Differentiating numerator and denominator separately:






= 3



Question 5.

Evaluate the following limits:



Answer:



Since the form is indeterminant



Method 1: factorization




Since a3 + b3 = (a + b)(a2 + b2 - ab)





= 1 + 1 + 1


= 3


Method 2: By L hospital rule:


Differentiating numerator and denominator separately:





= 12(-1/2)2


= 12/4


= 3



Question 6.

Evaluate the following limits:



Answer:



Since the form is indeterminant



Method 1: factorization









Method 2: By L hospital rule:


Differentiating numerator and denominator separately:







Question 7.

Evaluate the following limits:



Answer:



Since the form is indeterminant



Method 1: factorization





Since a2-b2 = (a + b)(a-b)





= (2 + 2)(22 + 22)


= 32


Method 2: By L hospital rule:


Differentiating numerator and denominator separately:





= 4(2)3


= 32



Question 8.

Evaluate the following limits:



Answer:



Since the form is indeterminant



Method 1: factorization









Method 2:


By L hospital rule:


Differentiating numerator and denominator separately:







Question 9.

Evaluate the following limits:



Answer:



Since the form is indeterminant



Method 1: factorization



Since a3 + b3 = (a + b)(a2 + b2-ab) & a2-b2 = (a + b)(a-b)




= (-1)2 + (1)2 - (-1)


= 3


Method 2: By L hospital rule:


Differentiating numerator and denominator separately:





= 3(-1)2


= 3



Question 10.

Evaluate the following limits:



Answer:



Since the form is indeterminant



Method 1: factorization





Since a3 + b3 = (a + b)(a2 + b2-ab) & a2-b2 = (a + b)(a-b)






=


=


= 25


Method 2: By L hospital rule:


Differentiating numerator and denominator separately:






= 25



Question 11.

Evaluate the following limits:



Answer:



Since the form is indeterminant



Method 1: factorization



Since a3 + b3 = (a + b)(a2 + b2-ab) & a2-b2 = (a + b)(a-b)









Method 2: By L hospital rule:


Differentiating numerator and denominator separately:








Question 12.

Evaluate the following limits:



Answer:



Since the form is



Method 1: factorization



Since a3 + b3 = (a + b)(a2 + b2-ab) & a2-b2 = (a + b)(a-b)









Method 2: By L hospital rule:


Differentiating numerator and denominator separately:








Question 13.

Evaluate the following limits:



Answer:



Since the form is



Method 1: factorization




Since a3 + b3 = (a + b)(a2 + b2-ab) & a2-b2 = (a + b)(a-b)








= 2


Method 2: By L hospital rule:


Differentiating numerator and denominator separately:






= 2



Question 14.

Evaluate the following limits:



Answer:





Since a2-b2 = (a + b)(a-b)






= 2



Question 15.

Evaluate the following limits:



Answer:







Hence,



Question 16.

Evaluate the following limits:



Answer:











Question 17.

Evaluate the following limits:



Answer:








Question 18.

Evaluate the following limits:



Answer:



Since the form is indeterminant



Method 1: factorization




Since a3 + b3 = (a + b)(a2 + b2-ab) & a2-b2 = (a + b)(a-b)






= 2


Method 2: By L hospital rule:


Differentiating numerator and denominator separately:





= 2



Question 19.

Evaluate the following limits:



Answer:



Since the form is indeterminant



Method 1: factorization




Since a3 + b3 = (a + b)(a2 + b2-ab) & a2-b2 = (a + b)(a-b)




Since a3 + b3 = (a + b)(a2 + b2-ab) & a2-b2 = (a + b)(a-b)




= (√4 + 2)(4 + 4)


= (2 + 2)(4 + 4)


= 32


Method 2: By L hospital rule:


Differentiating numerator and denominator separately:





= 4(4)3/2


= 32



Question 20.

Evaluate the following limits:



Answer:


Since the form is indeterminant



Method 1: factorization



Since a3 + b3 = (a + b)(a2 + b2-ab) & a2-b2 = (a + b)(a-b)





= 2a + 0


= 2a


Method 2: By L hospital rule:


Differentiating numerator and denominator separately:




= 2(a + 0)


= 2a



Question 21.

Evaluate the following limits:



Answer:





Since a3 + b3 = (a + b)(a2 + b2-ab) & a2-b2 = (a + b)(a-b)





= 1



Question 22.

Evaluate the following limits:



Answer:








Question 23.

Evaluate the following limits:



Answer:


Since a3 + b3 = (a + b)(a2 + b2-ab) & a2-b2 = (a + b)(a-b)








Question 24.

Evaluate the following limits:



Answer:

Since a3 + b3 = (a + b)(a2 + b2-ab) & a2-b2 = (a + b)(a-b)






= 6



Question 25.

Evaluate the following limits:



Answer:



Since the form is indeterminant



Method 1: factorization






Since a3-b3 = (a-b)(a2 + b2 + ab) & a2-b2 = (a + b)(a-b)





=


=


=


=


Method 2: By L hospital rule:


Differentiating numerator and denominator separately:








Question 26.

Evaluate the following limits:



Answer:



Since the form is indeterminant



Method 1: factorization



By long division method





Since a3-b3 = (a-b)(a2 + b2 + ab) & a2-b2 = (a + b)(a-b)






=


=



Method2: By L hospital rule:


Differentiating numerator and denominator separately:








Question 27.

Evaluate the following limits:



Answer:



Since the form is indeterminant



Method 1: factorization



Since a3-b3 = (a-b)(a2 + b2 + ab) & a2-b2 = (a + b)(a-b)







Method 2: By L hospital rule:


Differentiating numerator and denominator separately:








Question 28.

Evaluate the following limits:



Answer:



Since the form is indeterminant



Method 1: factorization










Method 2: By L hospital rule:


Differentiating numerator and denominator separately:








Question 29.

Evaluate the following limits:



Answer:



Since the form is



Method 1: factorization



By long division method





Since a3-b3 = (a-b)(a2 + b2 + ab) & a2-b2 = (a + b)(a-b)










Method 2: By L hospital rule:


Differentiating numerator and denominator separately:








Question 30.

Evaluate the following limits:



Answer:



Since the form is



Method 1: factorization



by dividing



Since a3-b3 = (a-b)(a2 + b2 + ab) & a2-b2 = (a + b)(a-b)









Method 2: By L hospital rule:


Differentiating numerator and denominator separately:








Question 31.

Evaluate the following limits:



Answer:
















Question 32.

Evaluate the following limits:



Answer:








Question 33.

Evaluate the following limits:



Answer:













= 2



Question 34.

Evaluate the following limits:



Answer:



Since the form is indeterminant



Method 1: factorization






Since a3-b3 = (a-b)(a2 + b2 + ab) & a2-b2 = (a + b)(a-b)









= 1


Method 2: By L hospital rule:


Differentiating numerator and denominator separately:






= 1




Exercise 29.4
Question 1.

Evaluate the following limits:



Answer:

Given


To find: the limit of the given equation when x tends to 0


Substituting x as 0, we get an indeterminant form of


Rationalizing the given equation



Formula: (a + b) (a - b) = a2 - b2





Now we can see that the indeterminant form is removed, so substituting x as 0


We get,



Question 2.

Evaluate the following limits:



Answer:

Given


To find: the limit of the given equation when x tends to 0


Substituting x as 0, we get an indeterminant form of


Rationalizing the given equation



Formula: (a + b) (a - b) = a2 - b2





Now we can see that the indeterminant form is removed, so substituting x as 0


We get



Question 3.

Evaluate the following limits:



Answer:

Given


To find: the limit of the given equation when x tends to 0


Substituting x as 0, we get an indeterminant form of


Rationalizing the given equation



Formula: (a + b) (a - b) = a2 - b2





Now we can see that the indeterminant form is removed, so substituting x as 0


We get,



Question 4.

Evaluate the following limits:



Answer:

Given


To find: the limit of the given equation when x tends to 0


Substituting x as 0 we get an indeterminant form of


Rationalizing the given equation



Formula: (a + b) (a - b) = a2 - b2





Now we can see that the indeterminant form is removed, so substituting x as 0


We get



Question 5.

Evaluate the following limits:



Answer:

Given


To find: the limit of the given equation when x tends to 2


Substituting x as 2, we get an indeterminant form of


Rationalizing the given equation



Formula: (a + b) (a - b) = a2 - b2





Now we can see that the indeterminant form is removed, so substituting x as 2


We get



Question 6.

Evaluate the following limits:



Answer:

Given


To find: the limit of the given equation when x tends to 3


Substituting x as 3, we get an indeterminant form of


Rationalizing the given equation



Formula: (a + b) (a - b) = a2 - b2






Now we can see that the indeterminant form is removed, so substituting x as 3


We get



Question 7.

Evaluate the following limits:



Answer:

Given


To find: the limit of the given equation when x tends to 0


Substituting x as 0, we find that it is in non-indeterminant form so by substituting x as 0 we will directly get the answer



We get as the answer



Question 8.

Evaluate the following limits:



Answer:

Given


To find: the limit of the given equation when x tends to 1


Substituting x as 1, we get an indeterminant form of


Rationalizing the given equation



Formula: (a + b) (a - b) = a2 - b2





Now we can see that the indeterminant form is removed, so substituting x as 1


We get



Question 9.

Evaluate the following limits:



Answer:

Given


To find: the limit of the given equation when x tends to 1


Substituting x as 1, we get an indeterminant form of


Rationalizing the given equation



Formula: (a + b) (a - b) = a2 - b2





Now we can see that the indeterminant form is removed, so substituting x as 1


We get



Question 10.

Evaluate the following limits:



Answer:

Given


To find: the limit of the given equation when x tends to 3


Substituting x as 3, we get an indeterminant form of


Rationalizing the given equation



Formula: (a + b) (a - b) = a2 - b2





Now we can see that the indeterminant form is removed, so substituting x as 3


We get



Question 11.

Evaluate the following limits:



Answer:

Given


To find: the limit of the given equation when x tends to 1


Substituting x as 1 we get an indeterminant form of


Rationalizing the given equation



Formula: (a + b) (a - b) = a2 - b2





Now we can see that the indeterminant form is removed, so substituting x as 1


We get



Question 12.

Evaluate the following limits:



Answer:

Given


To find: the limit of the given equation when x tends to 0


Substituting x as 0, we get an indeterminant form of


Rationalizing the given equation



Formula: (a + b) (a - b) = a2 - b2





Now we can see that the indeterminant form is removed, so substituting x as 0


We get



Question 13.

Evaluate the following limits:



Answer:

Given


To find: the limit of the given equation when x tends to 2


Substituting x as 2, we get an indeterminant form of


Rationalizing the given equation



Formula: (a + b) (a - b) = a2 - b2





Now we can see that the indeterminant form is removed, so substituting x as 2


We get



Question 14.

Evaluate the following limits:



Answer:

G iven


To find: the limit of the given equation when x tends to 2


Substituting x as 2, we get an indeterminant form of


Rationalizing the given equation



Formula: (a+ b) (a - b) = a2 - b2




Now we can see that the indeterminant form is removed, so substituting x as 2


We get



Question 15.

Evaluate the following limits:



Answer:

Given


To find: the limit of the given equation when x tends to 7


Substituting x as 7, we get an indeterminant form of


Rationalizing the given equation



Formula: (a+b) (a-b) = a2-b2





Now we can see that the indeterminant form is removed, so substituting x as 7


We get



Question 16.

Evaluate the following limits:



Answer:

Given


To find: the limit of the given equation when x tends to 0


Substituting x as 0, we get an indeterminant form of


Rationalizing the given equation,



Formula: (a + b) (a - b) = a2 - b2





Now we can see that the indeterminant form is removed, so substituting x as 0


We get



Question 17.

Evaluate the following limits:



Answer:

Given


To find: the limit of the given equation when x tends to 5


Substituting x as 5, we get an indeterminant form of


Rationalizing the given equation



Formula: (a + b) (a - b) = a2 - b2





Now we can see that the indeterminant form is removed, so substituting x as 5


We get



Question 18.

Evaluate the following limits:



Answer:

Given


To find: the limit of the given equation when x tends to 1


Substituting x as 1, we get an indeterminant form of


Rationalizing the given equation



Formula: (a + b) (a - b) = a2 - b2





Now we can see that the indeterminant form is removed, so substituting x as 1


We get



Question 19.

Evaluate the following limits:



Answer:

Given


To find: the limit of the given equation when x tends to 2


Substituting x as 2, we get an indeterminant form of


Rationalizing the given equation



Formula: (a + b) (a - b) = a2 - b2





Now we can see that the indeterminant form is removed, so substituting x as 2


We get



Question 20.

Evaluate the following limits:



Answer:

Given


To find: the limit of the given equation when x tends to 1


Substituting x as 1, we get an indeterminant form of


Rationalizing the given equation



Formula: (a + b) (a - b) = a2 - b2





Now we can see that the indeterminant form is removed, so substituting x as 1


We get



Question 21.

Evaluate the following limits:



Answer:

Given


To find: the limit of the given equation when x tends to 0


Substituting x as 0, we get an indeterminant form of


Rationalizing the given equation,



Formula: (a + b) (a - b) = a2 - b2





Now we can see that the indeterminant form is removed, so substituting x as 0


We get



Question 22.

Evaluate the following limits:



Answer:

Given


To find: the limit of the given equation when x tends to 0


Substituting x as 0, we get an indeterminant form of


Rationalizing the given equation



Formula: (a + b) (a - b) = a2 - b2





Now we can see that the indeterminant form is removed, so substituting x as 0


We get



Question 23.

Evaluate the following limits:



Answer:

Given


To find: the limit of the given equation when x tends to 4


Substituting x as 4, we get an indeterminant form of


Rationalizing the given equation



Formula: (a + b) (a - b) = a2 - b2




Now we can see that the indeterminant form is removed, so substituting x as 4


We get



Question 24.

Evaluate the following limits:



Answer:

Given


To find: the limit of the given equation when x tends to a


Substituting x as we get an indeterminant form of


Rationalizing the given equation



Formula: (a + b) (a - b) = a2 - b2




Now we can see that the indeterminant form is removed, so substituting x as a


We get



Question 25.

Evaluate the following limits:



Answer:

Given


To find: the limit of the given equation when x tends to 0


Substituting 0 as we get an indeterminant form of


Rationalizing the given equation



Formula: (a + b) (a - b) = a2 - b2





Now we can see that the indeterminant form is removed, so substituting x as 0


We get



Question 26.

Evaluate the following limits:



Answer:

Given


To find: the limit of the given equation when x tends to 0


Substituting 0 as we get an indeterminant form of


Rationalizing the given equation



Formula: (a + b) (a - b) = a2 - b2





Now we can see that the indeterminant form is removed, so substituting x as 0


We get



Question 27.

Evaluate the following limits:



Answer:

Given


To find: the limit of the given equation when x tends to 1


Substituting 1 as we get an indeterminant form of


Rationalizing the given equation



Formula: (a + b) (a - b) = a2 - b2





Now we can see that the indeterminant form is removed, so substituting x as 1


We get



Question 28.

Evaluate the following limits:



Answer:

Given


To find: the limit of the given equation when x tends to 1


Substituting 1 as we get an indeterminant form of


Rationalizing the given equation



Formula: (a + b) (a - b) = a2 - b2






Now we can see that the indeterminant form is removed, so substituting x as 1


We get



Question 29.

Evaluate the following limits:



Answer:

Given


To find: the limit of the given equation when x tends to 0


Substituting 0 as we get an indeterminant form of


Rationalizing the given equation



Formula: (a + b) (a - b) = a2 - b2






Now we can see that the indeterminant form is removed, so substituting x as 0


We get



Question 30.

Evaluate the following limits:



Answer:

Given


To find: the limit of the given equation when x tends to 1


Substituting 1 as we get an indeterminant form of


Rationalizing the given equation



Formula: (a + b) (a - b) = a2 - b2






Now we can see that the indeterminant form is removed, so substituting x as 1


We get



Question 31.

Evaluate the following limits:



Answer:

Given


To find: the limit of the given equation when h tends to 0


Substituting 0 as we get an indeterminant form of


Rationalizing the given equation



Formula: (a + b) (a - b) = a2 - b2





Now we can see that the indeterminant form is removed, so substituting h as 0


We get



Question 32.

Evaluate the following limits:



Answer:

Given


To find: the limit of the given equation when x tends to √10


Re-writing the equation as





Now rationalizing the above equation



Formula: (a + b) (a - b) = a2 - b2






Now we can see that the indeterminant form is removed, so substituting x as





Question 33.

Evaluate the following limits:



Answer:

Given


To find: the limit of the given equation when x tends to √6


Re-writing the equation as





Now rationalizing the above equation



Formula: (a + b) (a - b) = a2 - b2






Now we can see that the indeterminant form is removed, so substituting x as √6




Question 34.

Evaluate the following limits:



Answer:

Given


To find: the limit of the given equation when x tends to


Re-writing the equation as





Now rationalizing the above equation



Formula: (a + b) (a - b) = a2 - b2






Now we can see that the indeterminant form is removed, so substituting x as





Exercise 29.5
Question 1.

Evaluate the following limits:



Answer:

We need to find the limit for:


As limit can’t be find out simply by putting x = a because it is taking indeterminate form(0/0) form, so we need to have a different approach.


Let, Z =


Note: To solve the problems of limit similar to one in our question we use the formula mentioned below which can be derived using binomial theorem.


Formula to be used:


As Z does not match exactly with the form as described above so we need to do some manipulations–


Z =


⇒ Z =


Let x + 2 = y and a+2 = k


As x → a ; y → k


∴ Z =


Use the formula:


∴ Z =


Hence,



Question 2.

Evaluate the following limits:



Answer:

We need to find the limit for:


As limit can’t be find out simply by putting x = a because it is taking indeterminate form(0/0) form, so we need to have a different approach.


Let, Z =


Note: To solve the problems of limit similar to one in our question we use the formula mentioned below which can be derived using binomial theorem.


Formula to be used:


As Z does not match exactly with the form as described above so we need to do some manipulations–


Z =


⇒ Z =


Let x + 2 = y and a+2 = k


As x → a ; y → k


∴ Z =


Use the formula:


∴ Z =


Hence,



Question 3.

Evaluate the following limits:



Answer:

We need to find the limit for:


As limit can be find out simply by putting x = a because it is not taking indeterminate form(0/0) form, so we will be putting x = a


Let, Z =


⇒ Z =


This can be further simplified using a3 – 1 = (a–1)(a2 + a + 1)


⇒ Z =


⇒ Z = (1+a)4 + (1+a)2 + 1



Question 4.

Evaluate the following limits:



Answer:

We need to find the limit for:


As limit can’t be find out simply by putting x = a because it is taking indeterminate form(0/0) form, so we need to have a different approach.


Let, Z =


Note: To solve the problems of limit similar to one in our question we use the formula mentioned below which can be derived using binomial theorem.


Formula to be used:


As Z matches exactly with the form as described above so we don’t need to do any manipulations–


Z =


Use the formula:


∴ Z =


Hence,



Question 5.

Evaluate the following limits:



Answer:

We need to find the limit for:


As limit can’t be find out simply by putting x = a because it is taking indeterminate form(0/0) form, so we need to have a different approach.


Let, Z =


Note: To solve the problems of limit similar to one in our question we use the formula mentioned below which can be derived using binomial theorem.


Formula to be used:


As Z does not match exactly with the form as described above so we need to do some manipulations–


Z =


Dividing numerator and denominator by (x–a),we get


Z =


Using algebra of limits, we have –


Z =


Use the formula:


∴ Z =


Hence,



Question 6.

Evaluate the following limits:



Answer:

We need to find the limit for:


As limit can’t be find out simply by putting x = (–1/2) because it is taking indeterminate form(0/0) form, so we need to have a different approach.


Let, Z =


⇒ Z =


Note: To solve the problems of limit similar to one in our question we use the formula mentioned below which can be derived using binomial theorem.


Formula to be used:


As Z matches exactly with the form as described above so we don’t need to do any manipulations–


Z =


Let y = 2x


As x → –1/2 ⇒ 2x = y → –1


∴ Z =


Use the formula:


∴ Z =


Hence,



Question 7.

Evaluate the following limits:



Answer:

We need to find the limit for:


As limit can’t be find out simply by putting x = 27 because it is taking indeterminate form(0/0) form, so we need to have a different approach.


Let, Z =


Using algebra of limits, we have–


Z =


⇒ Z = (271/3 + 3) ×


⇒ Z = 6


Note: To solve the problems of limit similar to one in our question we use the formula mentioned below which can be derived using binomial theorem.


Formula to be used:


As Z matches exactly with the form as described above so we don’t need to do any manipulations–


Z = 6


Use the formula:


∴ Z =


Hence,



Question 8.

Evaluate the following limits:



Answer:

We need to find the limit for:


As limit can’t be find out simply by putting x = 4 because it is taking indeterminate form(0/0) form, so we need to have a different approach.


Let, Z =


Note: To solve the problems of limit similar to one in our question we use the formula mentioned below which can be derived using binomial theorem.


Formula to be used:


As Z does not match exactly with the form as described above so we need to do some manipulations–


Z =


Dividing numerator and denominator by (x–4),we get


Z =


Using algebra of limits, we have –


Z =


Use the formula:


∴ Z =


Hence,



Question 9.

Evaluate the following limits:



Answer:

We need to find the limit for:


As limit can’t be find out simply by putting x = 1 because it is taking indeterminate form(0/0) form, so we need to have a different approach.


Let, Z =


Note: To solve the problems of limit similar to one in our question we use the formula mentioned below which can be derived using binomial theorem.


Formula to be used:


As Z does not match exactly with the form as described above so we need to do some manipulations–


Z =


Dividing numerator and denominator by (x–1),we get


Z =


Using algebra of limits, we have –


Z =


Use the formula:


∴ Z =


Hence,



Question 10.

Evaluate the following limits:



Answer:

We need to find the limit for:


As limit can’t be find out simply by putting x = –1 because it is taking indeterminate form(0/0) form, so we need to have a different approach.


Let, Z =


Note: To solve the problems of limit similar to one in our question we use the formula mentioned below which can be derived using binomial theorem.


Formula to be used:


As Z does matches exactly with the form as described above so we don’t need to do any manipulations–


Z =


Use the formula:


∴ Z = 3(–1)3–1 = 3


Hence,



Question 11.

Evaluate the following limits:



Answer:

We need to find the limit for:


As limit can’t be find out simply by putting x = a because it is taking indeterminate form(0/0) form, so we need to have a different approach.


Let, Z =


Note: To solve the problems of limit similar to one in our question we use the formula mentioned below which can be derived using binomial theorem.


Formula to be used:


As Z does not match exactly with the form as described above so we need to do some manipulations–


Z =


Dividing numerator and denominator by (x–a),we get


Z =


Using algebra of limits, we have –


Z =


Use the formula:


∴ Z =


Hence,



Question 12.

If , find the value of n.


Answer:

Given,


, we need to find value of n


So we will first find the limit and then equate it with 108 to get the value of n.


We need to find the limit for:


As limit can’t be find out simply by putting x = a because it is taking indeterminate form(0/0) form, so we need to have a different approach.


Let, Z =


Note: To solve the problems of limit similar to one in our question we use the formula mentioned below which can be derived using binomial theorem.


Formula to be used:


As Z matches exactly with the form as described above so we don’t need to do any manipulations–


Z =


Use the formula:


∴ Z = n(3)n–1


According to question Z = 108


∴ n(3)n–1 = 108


To solve such equations, factorize the number into prime factors and try to make combinations such that one satisfies with the equation.


⇒ n(3)n–1 = 4× 27 = 4× (3)4–1


Clearly on comparison we have –


n = 4



Question 13.

if , find all possible values of a.


Answer:

Given,


, we need to find value of n


So we will first find the limit and then equate it with 9 to get the value of n.


We need to find the limit for:


As limit can’t be find out simply by putting x = a because it is taking indeterminate form(0/0) form, so we need to have a different approach.


Let, Z =


Note: To solve the problems of limit similar to one in our question we use the formula mentioned below which can be derived using binomial theorem.


Formula to be used:


As Z matches exactly with the form as described above so we don’t need to do any manipulations–


Z =


Use the formula:


∴ Z = 9(a)9–1 = 9a8


According to question Z = 9


∴ 9(a)8 = 9


⇒ a8 = 1 = 18 or (–1)8


Clearly on comparison we have –


a = 1 or –1



Question 14.

If , find all possible values of a.


Answer:

Given,


, we need to find value of n


So we will first find the limit and then equate it with 405 to get the value of n.


We need to find the limit for:


As limit can’t be find out simply by putting x = a because it is taking indeterminate form(0/0) form, so we need to have a different approach.


Let, Z =


Note: To solve the problems of limit similar to one in our question we use the formula mentioned below which can be derived using binomial theorem.


Formula to be used:


As Z matches exactly with the form as described above so we don’t need to do any manipulations–


Z =


Use the formula:


∴ Z = 5(a)5–1 = 5a4


According to question Z = 405


∴ 5(a)4 = 405


⇒ a4 = 81 = 34 or (–3)4


Clearly on comparison we have –


a = 3 or –3



Question 15.

If , find all possible values of a.


Answer:

Given,


, we need to find value of n


So we will first find the limit and then equate it with to get the value of n.


We need to find the limit for:


As limit can’t be find out simply by putting x = a because it is taking indeterminate form(0/0) form, so we need to have a different approach.


Let, Z =


Note: To solve the problems of limit similar to one in our question we use the formula mentioned below which can be derived using binomial theorem.


Formula to be used:


As Z matches exactly with the form as described above so we don’t need to do any manipulations–


Z =


Use the formula:


∴ Z = 9(a)9–1 = 9a8


According to question Z = = 4 + 5 = 9


∴ 9(a)8 = 9


⇒ a8 = 1 = 18 or (–1)8


Clearly on comparison we have –


a = 1 or –1



Question 16.

If , find all possible values of a.


Answer:

Given,






Note: To solve the problems of limit similar to one in our question we use the formula mentioned below which can be derived using binomial theorem.


Formula to be used:


Using the formula we have –


3a3–1 = 4(1)4–1


⇒ 3a2 = 4


⇒ a2 = 4/3


∴ a = ± (2/√3)




Exercise 29.6
Question 1.

Evaluate the following limits:



Answer:

Given:



then,



Hence,



Question 2.

Evaluate the following limits:



Answer:

Given:


Since, then



Hence,



Question 3.

Evaluate the following limits:



Answer:

Given:




Hence,



Question 4.

Evaluate the following limits:



Answer:

Given:

Rationalizing the numerator we get,





Taking x common from both numerator and denominator




Hence,



Question 5.

Evaluate the following limits:



Answer:

Given:

On rationalizing the numerator we get,






Hence,



Question 6.

Evaluate the following limits:



Answer:

Given:

On rationalizing the numerator we get,





Taking x common from both numerator and denominator





Hence,



Question 7.

Evaluate the following limits:



Answer:

Given:




Hence,



Question 8.

Evaluate the following limits:



Answer:

Given:

We know that,



By putting this Formula, we get,







Hence,



Question 9.

Evaluate the following limits:



Answer:

Given:



Hence,



Question 10.

Evaluate the following limits:



Answer:

Given:


Rationalizing the numerator and denominator we get,











Hence,



Question 11.

Evaluate the following limits:



Answer:

Given:

We know that,


(n + 2)! = (n + 2) × (n + 1)!


By putting the value of (n+2)! , we get









Hence,



Question 12.

Evaluate the following limits:



Answer:

Given:

On Rationalizing the Numerator we get,










Hence, = 1



Question 13.

Evaluate the following limits:



Answer:

Given:

On Rationalizing the numerator we get,




Dividing the numerator and the denominator by √x, we get,





Hence,



Question 14.

Evaluate the following limits:



Answer:

Given:

Formula Used:



Now, Putting this formula and we get,





Taking x3 as common and we get,



Since, then,



Hence,



Question 15.

Evaluate the following limits:



Answer:

Given:

Taking LCM then, we get,



Therefore,



By putting this, we get,






Hence,



Question 16.

Evaluate the following limits:



Answer:

Given:

Here we know that,









Since,



Hence,



Question 17.

Evaluate the following limits:



Answer:

Formula Used:



Given:


By putting this, in the given equation, we get,







Taking x4 as common,



Hence,



Question 18.

Evaluate the following limits:



Answer:


Now, Rationalizing the Numerator, we get,








Hence,



Question 19.

Evaluate the following limits:



Answer:

……(1)

We can see that this is a geometric progression with the common ratio 1/3.


And, we know the sum of n terms of GP is


Let suppose, and , then






Now, putting the value of Sn in equation (1), we get




Hence,



Question 20.

Evaluate the following limits:

, where a is a non-zero real number.


Answer:

Give:

Now, Taking x4 as common from both numerator and denominator,





Hence, a = 1



Question 21.

Evaluate the following limits:

and , then prove that f(-2) = f(2) = 1.


Answer:

Given:

To Prove: f(-2) = f(2) = 1.


Proof: we have,


And,




Therefore, b = 1


Also,




b = 1


Thus,


On substituting the value of a and b we get,




So, f(x) = 1


Then, f(-2) = 1


Also, f(2) = 1


Hence, f(2)=f(-2)=1



Question 22.

Show that

To Prove:


Answer:

We have L.H.S

Rationalizing the numerator, we get,




Taking x as common from both numerator and denominator,





Therefore,


Now , Take R.H.S







Now then


Therefore, R.H.S = 0


So, L.H.S ≠ R.H.S


Hence,



Question 23.

Evaluate the following limits:



Answer:

Rationalizing the numerator, we get




Taking x as common from both numerator and denominator,



Now then



Hence, .



Question 24.

Evaluate the following limits:



Answer:

Rationalizing the numerator, we get




Taking x as common from both numerator and denominator,



Now then



Hence, .



Question 25.

Evaluate:



Answer:

Formula Used:



Now putting these value, we get,





Now then,



=



Question 26.

Evaluate:



Answer:

Here We know,



By putting these value, we get,








Hence,




Exercise 29.7
Question 1.

Evaluate the following limits:



Answer:




Multiplying and Dividing by 3:




As, x → 0 ⇒ 3x → 0



Now, put 3x = y



Formula used:



Therefore,






Hence the value of



Question 2.

Evaluate the following limits:



Answer:






Multiplying and Dividing by








Formula used:



Therefore,






Hence, the value of



Question 3.

Evaluate the following limits:



Answer:




As, x → 0 ⇒ x2 → 0






Formula used:



Therefore,





=1


Hence, the value of



Question 4.

Evaluate the following limits:



Answer:





We know,



Therefore,



Formula used:






{∵ cos 0 = 1}



Hence, the value of



Question 5.

Evaluate the following limits:



Answer:


We know,


Sin3x = 3sinx – 4 sin3x


Therefore,




Multiplying and Dividing by 3:




As, x → 0 ⇒ 3x → 0



Now, put 3x = y



Formula used:



Therefore,




= 3 × 1


= 3


Hence, the value of



Question 6.

Evaluate the following limits:



Answer:



Multiplying and Dividing by 8x in numerator & Multiplying and Dividing by 2x in the denominator:





We know,



Therefore,



As, x → 0 ⇒ 8x → 0 & 2x → 0



Now, put 2x = y and 8x = t



Formula used:



Therefore,





= 4


Hence, the value of



Question 7.

Evaluate the following limits:



Answer:



Multiplying and Dividing by mx in numerator & Multiplying and Dividing by nx in the denominator:





We know,



Therefore,



As, x → 0 ⇒ mx → 0 & nx → 0



Now, put mx = y and nx = t



Formula used:



Therefore,






Hence, the value of



Question 8.

Evaluate the following limits:



Answer:



Multiplying and Dividing by 5x in numerator & Multiplying and Dividing by 3x in the denominator:





We know,



Therefore,



As, x → 0 ⇒ 5x → 0 & 3x → 0



Now, put 5x = y and 3x = t



Formula used:



Therefore,






Hence, the value of



Question 9.

Evaluate the following limits:



Answer:


We know,









Formula used:



Therefore,




= 1


Hence, the value of



Question 10.

Evaluate the following limits:



Answer:



Dividing numerator and denominator by x:




We know,



Therefore,



Formula used:



Therefore,





{∵ cos 0 = 1}




Hence, the value of



Question 11.

Evaluate the following limits:



Answer:


We know,



Therefore,





Multiplying and Dividing by in numerator &


similarly byin denominator, we get,



We know,



Therefore,







Formula used:



Therefore,




Now, put values of m, n, k and l:







Hence, the value of



Question 12.

Evaluate the following limits:



Answer:




Multiplying and dividing by 32 :






Formula used:



Therefore,




= 9


Hence, the value of



Question 13.

Evaluate the following limits:



Answer:


We know,


cos 2x = 1 – 2 sin2 x







Multiplying and dividing by








Formula used:



Therefore,





Hence, the value of



Question 14.

Evaluate the following limits:



Answer:



Dividing numerator and denominator by 6x:





We know,



Therefore,



As, x → 0 ⇒ 2x → 0 & 3x → 0



Put 2x = y and 3x = k;



Formula used:



Therefore,









Hence, the value of



Question 15.

Evaluate the following limits:



Answer:


We know,



Therefore,






Multiplying and dividing by 10:



As,


x → 0 ⇒ 2x → 0 & 5x → 0




Put 2x = y and 5x = k;



Formula used:



Therefore,




=20 × 1


= 20


Hence, the value of



Question 16.

Evaluate the following limits:



Answer:



Multiplying and Dividing by 3θ in numerator & Multiplying and Dividing by 2θ in the denominator:





We know,



Therefore,



As, x → 0 ⇒ 3θ → 0 & 2θ → 0



Now, put 3θ = y and 2θ = t



Formula used:



Therefore,






Hence, the value of



Question 17.

Evaluate the following limits:



Answer:


We know,


cos 2x = 1 – 2 sin2 x
















Formula used:



Therefore,





Hence, the value of



Question 18.

Evaluate the following limits:



Answer:






As, x → 0 ⇒ x2→ 0 ⇒ 4x2 → 0



Put x2 = y



Formula used:



Therefore,


= 16 × (1)2


= 16


Hence, the value of



Question 19.

Evaluate the following limits:



Answer:



Dividing numerator and denominator by x:




We know,



Therefore,



Formula used:



Therefore,





{∵ cos 0 = 1}




= 3


Hence, the value of



Question 20.

Evaluate the following limits:



Answer:



Dividing numerator and denominator by x:





We know,



Therefore,



Formula used:



Therefore,






Hence, the value of



Question 21.

Evaluate the following limits:



Answer:



Dividing numerator and denominator by x:




We know,



Therefore,



Formula used:



Therefore,





{∵ cos 0 = 1}




= 8


Hence, the value of



Question 22.

Evaluate the following limits:



Answer:


We know,



Therefore,









{∵ cos 0 = 1}


= 2 × 1


= 2


Hence, the value of



Question 23.

Evaluate the following limits:



Answer:


We know,



Therefore,







=2 × cos(4 × 0


=2 × cos 0


{∵ cos 0 = 1}


= 2 × 1


= 2


Hence, the value of



Question 24.

Evaluate the following limits:



Answer:


We know,



Therefore,






Multiplying and dividing by 10:



As,


X → 0 ⇒ 4x → 0




Put 4x = k;



Formula used:



Therefore,




= 8 × 1


= 8


Hence, the value of



Question 25.

Evaluate the following limits:



Answer:



Dividing numerator and denominator by x:





We know,



Therefore,







Put 3x = y:



Formula used:



Therefore,







Hence , the value of



Question 26.

Evaluate the following limits:



Answer:


We know,



Therefore,








Formula used:



Therefore,




= 2 cos 2 × 1


= 2 cos 2


Hence, the value of



Question 27.

Evaluate the following limits:



Answer:


We know,


(a + b)2 = a2 + b2 + 2ab


Therefore,






Now,




We get,






Formula used:



Therefore,






Hence, the value of



Question 28.

Evaluate the following limits:



Answer:


We know,








{∵ sin2 x = 1 – cos2 x}



{∵ a2 – b2 = (a – b) (a+b)}




{∵ cos 0 = 1}





Hence, the value of



Question 29.

Evaluate the following limits:



Answer:


We know,








We know,









We know,



Therefore,



As, x → 0 ⇒ 3x → 0 & 4x → 0



Put 2x = y & 4x = t:



Formula used:



Therefore,






= 2


Hence, the value of



Question 30.

Evaluate the following limits:



Answer:


We know,



cos2x = 1 – 2sin2x


⇒ 2sin2x = 1 – cos2x






Dividing numerator and denominator by x2:




We know,



Therefore,







Put 3x = y & 5x = t:



Formula used:



Therefore,






Hence, the value of



Question 31.

Evaluate the following limits:



Answer:


Now, 1 - cos2x = 2 sin2x






Since,




Hence,



Question 32.

Evaluate the following limits:



Answer:








Since,




Question 33.

Evaluate the following limits:



Answer:








Question 34.

Evaluate the following limits:



Answer:


Rationalize the numerator, we get









Hence,



Question 35.

Evaluate the following limits:



Answer:









Hence,



Question 36.

Evaluate the following limits:



Answer:







Hence,



Question 37.

Evaluate the following limits:



Answer:


Since,






= -2(1 × 2) × 2 × 1


Hence,



Question 38.

Evaluate the following limits:



Answer:










Hence,



Question 39.

Evaluate the following limits:



Answer:







Since,




Hence,



Question 40.

Evaluate the following limits:



Answer:


Since, 1 - cos 2x = 2sin2x





Since,



Hence,



Question 41.

Evaluate the following limits:



Answer:






= 2 cos 3


Hence,



Question 42.

Evaluate the following limits:



Answer:


We know that, cos2x = 1 – 2sin2x


Therefore,





[cos2x – 1 = (cosx + 1)(cosx – 1)]



= 2(1 + 0)


= 2


Hence,



Question 43.

Evaluate the following limits:



Answer:




Since,




Hence,



Question 44.

Evaluate the following limits:



Answer:







Hence,



Question 45.

Evaluate the following limits:



Answer:






Hence,



Question 46.

Evaluate the following limits:



Answer:





Hence,



Question 47.

Evaluate the following limits:



Answer:


Since, 1 - cos2x = 2sin2 x







Hence,



Question 48.

Evaluate the following limits:



Answer:







Hence,



Question 49.

Evaluate the following limits:



Answer:





Hence,



Question 50.

Evaluate the following limits:



Answer:





Hence,



Question 51.

Evaluate the following limits:



Answer:


Since, sin 2x = 2 sinx .cos x











Hence,



Question 52.

Evaluate the following limits:



Answer:






Hence,



Question 53.

Evaluate the following limits:



Answer:

Given,







Hence,



Question 54.

Evaluate the following limits:



Answer:

Given,

Now, divide by x






Hence,



Question 55.

Evaluate the following limits:



Answer:

Given,






Hence,



Question 56.

Evaluate the following limits:



Answer:

Given,

Since, sin3x = 3sinx - 4sin3x





= 4 × 1


Hence,



Question 57.

Evaluate the following limits:



Answer:


Put









= 4


Hence,



Question 58.

Evaluate the following limits:



Answer:

Given,

Taking x as common, we get





= 1


Hence,



Question 59.

Evaluate the following limits:



Answer:

Given,






= 0


Hence,



Question 60.

Evaluate the following limits:



Answer:

Here,








Hence,



Question 61.

Evaluate the following limits:



Answer:


Explanation: Here,







Hence,



Question 62.

Evaluate the following limits:



Answer:

Given,

Explanation:








Hence,



Question 63.

Evaluate the following limits:

If


Answer:

Given,

To Find: Value of k?


Explanation: Here,



Taking k common from L.H.S and multiply and divide by k in R.H.S, we get




K2 = 1


K = ±1


Hence, The value of k is 1, - 1.




Exercise 29.8
Question 1.

Evaluate the following limits:



Answer:

Given:

Assumption: Let y


So,








Hence,



Question 2.

Evaluate the following limits:



Answer:

Given,

We know, sin2x = 2sin x.cos x


By putting this value, we get






Hence



Question 3.

Evaluate the following limits:



Answer:

Given,

Here, cos2 x = 1-sin2x


By putting this we get,







Hence,



Question 4.

Evaluate the following limits:



Answer:

Given,

[Applying the formula 1 – cos 2x = 2sin2x]






We know that, sin x = sin(π – x)


Therefore,




Hence,



Question 5.

Evaluate the following limits:



Answer:

Given,






Hence,



Question 6.

Evaluate the following limits:



Answer:

Given,






We know,



Hence,



Question 7.

Evaluate the following limits:



Answer:

We have Given, If

If






Since,



Hence,



Question 8.

Evaluate the following limits:



Answer:

We have


If


Let









Hence,



Question 9.

Evaluate the following limits:



Answer:

Given ,


Let t = x - a


Then, as x→a, t→0








Hence,



Question 10.

Evaluate the following limits:



Answer:

We have


Rationalise the numerator, we get









Hence,



Question 11.

Evaluate the following limits:



Answer:

Given,




Now, rationalize the Numerator, we get,









Hence,



Question 12.

Evaluate the following limits:



Answer:

Given,

Now,











Hence,



Question 13.

Evaluate the following limits:



Answer:

Given,

Where














Hence,



Question 14.

Evaluate the following limits:



Answer:

We have Given,


Now, Rationalize the Denominator






Hence,



Question 15.

Evaluate the following limits:



Answer:

Given,

If x → π, then π – x → 0, let π – x = y




Rationalize the Numerator









Hence,



Question 16.

Evaluate the following limits:



Answer:

We have Given,


Now, Rationalize the Denominator





Hence,



Question 17.

Evaluate the following limits:



Answer:

we have







Question 18.

Evaluate the following limits:



Answer:

We have Given,


Here, x → 1, then x – 1 → 0, let x – 1 = y











Hence,



Question 19.

Evaluate the following limits:

, where f(x) = sin 2x


Answer:

Given, f(x) = sin 2x

Since,




Now,








Since,



Hence,



Question 20.

Evaluate the following limits:



Answer:

Given,

Now,








Hence,



Question 21.

Evaluate the following limits:



Answer:

We have Given,


Here, x → 1, then x – 1 → 0, let x – 1 = y









Hence,



Question 22.

Evaluate the following limits:



Answer:

We have







Since, , then




Hence,



Question 23.

Evaluate the following limits:



Answer:

Given,

As we know, tan2x = sec2x - 1








Hence,



Question 24.

Evaluate the following limits:



Answer:


Divide and multiply by 2, we get




Now,







Hence,



Question 25.

Evaluate the following limits:



Answer:

We have




Now,




We know, then, we get



Hence,



Question 26.

Evaluate the following limits:



Answer:

We have


Now,




We know, then , we get




Hence,



Question 27.

Evaluate the following limits:



Answer:

We have










Hence,



Question 28.

Evaluate the following limits:



Answer:

We have








Hence,



Question 29.

Evaluate the following limits:



Answer:

We have


When,









Hence,



Question 30.

Evaluate the following limits:



Answer:

We have




Since,



By putting these , we get









Since,





Hence,



Question 31.

Evaluate the following limits:



Answer:

We have Given,











Hence,



Question 32.

Evaluate the following limits:



Answer:


Rationalizing we get,




As,


Therefore, y → 0,


Now,






Hence,



Question 33.

Evaluate the following limits:



Answer:

We have Given,

if x → 1 then, x – 1 → 0 let x – 1 = y








Hence,



Question 34.

Evaluate the following limits:



Answer:

[cosec2x – cot2x = 1]



[Applying, a2 – b2 = (a + b)(a – b)]



Hence,



Question 35.

Evaluate the following limits:



Answer:

We have Given ,


Now,




Here, cos(a+b) =cos a.cos b – sin a.sin b


And, sin(a+b) = sin a.cos b+cos a.sin b










Hence,



Question 36.

Evaluate the following limits:



Answer:

We have Given,






Hence,



Question 37.

Evaluate the following limits:



Answer:

We have Given,











Hence, the answer is 1.


Question 38.

Evaluate the following limits:



Answer:







Hence,





Exercise 29.9
Question 1.

Evaluate the following limits:



Answer:

As we need to find


We can directly find the limiting value of a function by putting the value of the variable at which the limiting value is asked if it does not take any indeterminate form (0/0 or ∞/∞ or ∞-∞, .. etc.)


Let Z


∴ we need to take steps to remove this form so that we can get a finite value.


Tip: Similar limit problems involving trigonometric ratios are mostly solved using sandwich theorem.


So to solve this problem we need to have a sin term so that we can make use of sandwich theorem.


Note: While modifying be careful that you don’t introduce any zero terms in the denominator


As,


Multiplying numerator and denominator by 1-cos x, We have-



⇒ Z =


{As 1-cos2x = sin2x}


⇒ Z =





To apply sandwich theorem, we need to have limit such that variable tends to 0 and following forms should be there


Here x→ π so we need to do modifications before applying the theorem.


As, sin (π-x) = sin x or sin (x - π) = -sin x and tan(π – x) = -tan x


∴ we can say that-


sin2x = sin2(x-π) and tan2x = tan2(x-π)


As x → π


∴ (x – π) → 0


Let us represent x - π with y


∴ Z =


Dividing both numerator and denominator by y2


Z =


⇒ Z = {Using basic limits algebra}


As,


∴ Z =




Question 2.

Evaluate the following limits:



Answer:

As we need to find


We can directly find the limiting value of a function by putting the value of the variable at which the limiting value is asked if it does not take any indeterminate form (0/0 or ∞/∞ or ∞-∞, .. etc.)


Let Z =


∴ we need to take steps to remove this form so that we can get a finite value.


Note: While modifying be careful that you don’t introduce any zero terms in the denominator


As





⇒ Z =


{Using basic limits algebra}



∵ (1- 2sin2x) = cos 2x




As, a2 – b2 = (a+b)(a-b)


⇒ Z =


Now put the value of x, we have-


∴ Z =


Hence,




Question 3.

Evaluate the following limits:



Answer:

As we need to find


We can directly find the limiting value of a function by putting the value of the variable at which the limiting value is asked if it does not take any indeterminate form (0/0 or ∞/∞ or ∞-∞, .. etc)


Let


∴ we need to take steps to remove this form so that we can get a finite value.


Note: While modifying be careful that you don’t introduce any zero terms in the denominator


As Z =


As, a2 – b2 = (a+b)(a-b)


∴ Z =


⇒ Z =


⇒ Z =


⇒ Z =


Multiplying cosec x + 2 to both numerator and denominator-


Z =


Z =


As, cosec2x – 1 = cot2 x


∴ Z =


⇒ Z =




Question 4.

Evaluate the following limits:



Answer:

As we need to find


We can directly find the limiting value of a function by putting the value of the variable at which the limiting value is asked if it does not take any indeterminate form (0/0 or ∞/∞ or ∞-∞, .. etc.)


Let Z =


∴ we need to take steps to remove this form so that we can get a finite value.


Note: While modifying be careful that you don’t introduce any zero terms in the denominator


As


∵ cosec2x – 1 = cot2x



As, a2 – b2 = (a+b)(a-b)


Thus,




Hence,




Question 5.

Evaluate the following limits:



Answer:

As we need to find


We can directly find the limiting value of a function by putting the value of the variable at which the limiting value is asked if it does not take any indeterminate form (0/0 or ∞/∞ or ∞-∞, .. etc.)


Let


∴ we need to take steps to remove this form so that we can get a finite value.


Note: While modifying be careful that you don’t introduce any zero terms in the denominator


As Z =


Multiplying numerator and denominator by √(2+cos x) + 1,we have-


Z =


⇒ Z =


{using a2 – b2 = (a+b)(a-b)}


⇒ Z =


{using basic algebra of limits}


⇒ Z = =


As, 1+cos x = 2cos2(x/2)


∴ Z =


Tip: Similar limit problems involving trigonometric ratios along with algebraic equations are mostly solved using sandwich theorem.


So to solve this problem we need to have a sin term so that we can make use of sandwich theorem.


∵ sin(π/2 – x) = cos x


∴ Z =


As x→π ⇒ π – x → 0


Let y = π – x


Z =


To apply sandwich theorem we have to get the similar form as described below-



∴ Z =


⇒ Z =


Hence,




Question 6.

Evaluate the following limits:



Answer:

As we need to find


We can directly find the limiting value of a function by putting the value of the variable at which the limiting value is asked if it does not take any indeterminate form (0/0 or ∞/∞ or ∞-∞, .. etc.)


Let Z =


∴ Z is not taking an indeterminate form.


∴ Limiting the value of Z is not defined.


Hence,