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Algebraic Expression, Identities And Factorisation

Class 8th Mathematics NCERT Exemplar Solution
Exercise
  1. The product of a monomial and a binomial is aA. monomial B. binomial C. trinomial…
  2. In a polynomial, the exponents of the variables are alwaysA. integers B. positive…
  3. Which of the following is correct?A. (a - b)^2 = a^2 + 2ab - b^2 B. (a - b)^2 =…
  4. The sum of -7pq and 2pq isA. -9pq B. 9 pq C. 5 pq D. -5 pq
  5. If we subtract -3x^2 y^2 from x^2 y^2 , then we getA. -4x^2 y^2 B. -2x^2 y^2 C.…
  6. Like term as 4m^3 n^2 isA. 4m^2 n^2 B. -6m^3 n^2 C. 6pm^3 n^2 D. 4m^3 n…
  7. Which of the following is a binomial?A. 7 × a + a B. 6a^2 + 7b + 2c C. 4a × 3b ×…
  8. Sum of a - b + ab, b + c - bc and c - a - ac isA. 2c + ab - ac - bc B. 2c - ab -…
  9. Product of the following monomials 4p, -7q^3 , -7pq isA. 196p^2 q^4 B. 196 pq^4 C.…
  10. Area of a rectangle with length 4ab and breadth 6b^2 isA. 24a^2 b^2 B. 24 ab^3 C.…
  11. Volume of a rectangular box (cuboid) with length = 2ab, breadth = 3 ac and height…
  12. Product of 6a^2 - 7b + 5ab and 2ab isA. 12a^3 b - 14ab^2 + 10ab B. 12a^3 b -…
  13. Square of 3x - 4y isA. 9x^2 - 16y^2 B. 6x^2 - 8y^2 C. 9x^2 + 16y^2 + 24xy D. 9x^2…
  14. Which of the following are like terms?A. 5xyz^2 , -3xy^2 z B. -5xyz^2 , 7xyz^2 C.…
  15. Coefficient of y in the term -y/3 isA. -1 B. -3 C. -1/3 D. 1/3
  16. a^2 - b^2 is equal toA. (a - b)^2 B. (a - b) (a - b) C. (a + b) (a - b) D. (a +…
  17. Common factor of 17 abc, 34ab^2 , 51a^2 b isA. 17abc B. 17 ab C. 17 ac D. 17a^2…
  18. Square of 9x - 7xy isA. 81x^2 + 49x^2 y^2 B. 81x^2 - 49x^2 y^2 C. 81x^2 + 49x^2…
  19. Factorised form of 23xy - 46x + 54y - 108 isA. (23x + 54) (y 2) B. (23x + 54y) (y…
  20. Factorised form of r^2 -10r + 21 isA. (r-1)(r-4) B. (r-7)(r-3) C. (r-7)(r+3) D.…
  21. Factorised form of p^2 - 17p - 38 isA. (p-19) (p+2) B. (p-19) (p-2) C. (p+19)…
  22. On dividing 57p^2 qr by 114pq, we getA. 1/4 pr B. 3/4 pr C. 1/2 pr D. 2 pr…
  23. On dividing p (4p2 - 16) by 4p (p - 2), we getA. 2p+4 B. 2p-4 C. p+2 D. p-2…
  24. The common factor of 3ab and 2cd isA. 1 B. -1 C. a D. c
  25. An irreducible factor of 24x^2 y^2 isA. x^2 B. y^2 C. x D. 24x
  26. Number of factors of (a + b)^2 isA. 4 B. 3 C. 2 D. 1
  27. The factorised form of 3x - 24 isA. 3x × 24 B. 3 (x - 8) C. 24 (x - 3) D. 3 (x -…
  28. The factors of x^2 - 4 areA. (x - 2), (x - 2) B. (x + 2), (x - 2) C. (x + 2), (x…
  29. The value of (-27x^2 y) ÷ (-9xy) isA. 3xy B. -3xy C. -3x D. 3x
  30. The value of (3x^3 + 9x^2 + 27x) ÷ 3x isA. 2a + 2b B. 2a - 2b C. 2a^2 + 2b^2 D.…
  31. The value of (3x^3 +9x^2 + 27x) ÷ 3x is (a) x^2 +9 + 27x (b) 3x^3 +3x^2 + 27x (c)…
  32. The value of (a + b)^2 + (a - b)^2 is: (a) 2a + 2b (b) 2a - 2b (c) 2a^2 + 2b^2…
  33. The value of (a + b)^2 - (a - b)^2 is (a) 4ab (b) - 4ab (c) 2a^2 + 2b^2 (d) 2a2 -…
  34. The product of two terms with like signs is a………… term. Fill in the blanks to…
  35. The product of two terms with unlike signs is a …………….. term. Fill in the blanks…
  36. a (b + c) = ax ……….. × ax ……….. . Fill in the blanks to make the statements true:…
  37. (a - b) …………….. = a^2 - 2ab + b^2 Fill in the blanks to make the statements true:…
  38. a^2 - b^2 = (a + b) …………… . Fill in the blanks to make the statements true:…
  39. (a - b)^2 + ……….. = a^2 - b^2 Fill in the blanks to make the statements true:…
  40. (a + b)^2 - 2ab = ……… + ……… . Fill in the blanks to make the statements true:…
  41. (x + a) (x + b) = x^2 + (a + b)x + ……….. . Fill in the blanks to make the…
  42. The product of two polynomials is a ………. . Fill in the blanks to make the…
  43. Common factor of ax^2 + bx is ……….. . Fill in the blanks to make the statements…
  44. Factorised form of 18mn + 10mnp is ……… . Fill in the blanks to make the…
  45. Factorised form of 4y^2 - 12y + 9 is ……… . Fill in the blanks to make the…
  46. 38x3y2z÷ 19xy^2 is equal to ………. . Fill in the blanks to make the statements…
  47. Volume of a rectangular box with length 2x, breadth 3y and height 4z is ……………. .…
  48. 67^2 - 37^2 = (67 - 37) × ……………. = ………… . Fill in the blanks to make the…
  49. 103^2 - 102^2 = ………….. × (103 - 102) = ……… . Fill in the blanks to make the…
  50. Area of a rectangular plot with side 4x^2 and 3y^2 is ……….. . Fill in the blanks…
  51. Volume of a rectangular box with l = b = h = 2x is …………. . Fill in the blanks to…
  52. The coefficient in - 37abc is …………. . Fill in the blanks to make the statements…
  53. Number of terms in the expression a^2 + bc ×d is ……………. . Fill in the blanks to…
  54. The sum of areas of two squares with sides 4a and 4b is ………………. . Fill in the…
  55. The common factor method of factorisation for a polynomial is based on …………..…
  56. The side of the square of area 9y^2 is ………. . Fill in the blanks to make the…
  57. On simplification 3x+3/3 = …….. . Fill in the blanks to make the statements true:…
  58. The factorisation of 2x + 4y is ………. . Fill in the blanks to make the statements…
  59. (a + b)^2 = a^2 + b^2 State whether the statements are true (T) or false (F).…
  60. (a - b)^2 = a^2 - b^2 State whether the statements are true (T) or false (F).…
  61. (a + b) (a - b) = a^2 - b^2 State whether the statements are true (T) or false…
  62. The product of two negative terms is a negative term. State whether the…
  63. The product of one negative and one positive term is a negative term. State…
  64. The coefficient of the term -6x^2 y^2 is -6. State whether the statements are…
  65. p^2 q + r^2 r + r^2 q is a binomial. State whether the statements are true (T) or…
  66. The factors of a^2 - 2ab + b^2 are (a+b) and (a+b). State whether the statements…
  67. h is a factor of 2π (h+r). State whether the statements are true (T) or false…
  68. Some of the factors of n^2/2 + n/2 are , 1/2 , n and (n+1). State whether the…
  69. An equation is true for all values of its variables. State whether the statements…
  70. x^2 + (a+b)x + ab = (a+b) (x+ab) State whether the statements are true (T) or…
  71. Common factor of 11pq^2 , 121p^2 q^3 , 1331p^2 q is 11p^2 q^2 . State whether the…
  72. Common factor of 12a^2 b^2 +4ab^2 -32 is 4. State whether the statements are true…
  73. Factorisation of -3a^2 +3ab+3ac is 3a(-a-b -c). State whether the statements are…
  74. Factorised form of p^2 +30p+216 is (p+18) (p-12). State whether the statements…
  75. The difference of the squares of two consecutive numbers is their sum. State…
  76. abc + bca + cab is a monomial. State whether the statements are true (T) or false…
  77. On dividing p/3 by 3/p , the quotient is 9. State whether the statements are true…
  78. The value of p for 51^2 - 49^2 = 100p is 2. State whether the statements are true…
  79. (9x - 51) ÷ 9 is x - 51. State whether the statements are true (T) or false (F).…
  80. The value of (a+1) (a-1) (a^2 +1) is a^4 -1 State whether the statements are true…
  81. 7a^2 bc, -3abc^2 , 3a^2 bc, 2abc^2 Add:
  82. 9ax, + 3by - cz, -5by + ax + 3cz Add:
  83. xy^2 z^2 + 3x^2 y^2 z-4x^2 yz^2 ,-9x^2 y^2 z + 3xy^2 z^2 + x^2 yz^2 Add:…
  84. 5x^2 - 3xy + 4y^2 - 9, 7y^2 + 5xy - 2x^2 + 13 Add:
  85. 2p^4 - 3p^3 + p^2 - 5p + 7, -3p^4 -7p^3 -3p^2 -p-12 Add:
  86. Add: 3a(a-b-c), 2b (a-b + c)
  87. 3a (2b + 5c), 3c (2a + 2b) Add:
  88. 5a^2 b^2 c^2 from -7a^2 b^2 c^2 Subtract:
  89. 6x^2 - 4xy + 5y^2 from 8y^2 + 6xy - 3x^2 Subtract:
  90. 2a^2 b^2 c^2 + 4a^2 b^2 c - 5a^2 bc^2 from -10a^2 b^2 c + 4ab^2 c^2 + 2a^2 bc^2…
  91. 3t^4 -4t^3 + 2t^2 -6t + 6 from -4t^4 + 8t^3 -4t^2 -2t + 11 Subtract:…
  92. 2ab + 5bc-7ac from 5ab-2bc-2ac + 10abc Subtract:
  93. 7p (3q + 7p) from 8p (2p -7q) Subtract:
  94. -3p^2 + 3pq + 3px from 3p (-p-a-r) Subtract:
  95. -7pq^2 r^3 , -13p3q^2 r Multiply the following:
  96. 3x^2 y^2 z^2 , 17xyz Multiply the following:
  97. 15xy^2 , 17yz^2 Multiply the following:
  98. -5a^2 bc, 11ab, 12abc^2 Multiply the following:
  99. -3x^2 y, (5y - xy) Multiply the following:
  100. abc, (bc + ca) The multiplication is as follows: (vii) 7prq, (p - q + r)…
  101. x^2 y^2 z^2 , (xy - yz + zx) Multiply the following:
  102. (p + 6), (q - 7) Multiply the following:
  103. 6mn, 0mn Multiply the following:
  104. a, a^5 , a^6 Multiply the following:
  105. b^3 , 3b^2 , 7ab^5 Multiply the following:
  106. -7st, -1, -12st^2 Multiply the following:
  107. - 100/9 rs; 3/4 r^3 s^2 Multiply the following:
  108. (a^2 - b^2), (a^2 + b^2) Multiply the following:
  109. (ab + c), (ab + c) Multiply the following:
  110. (pq- 2r), (pq- 2r) Multiply the following:
  111. (3/4 x - 4/3 y) , (2/3 x + 3/2 y) Multiply the following:
  112. 3/2 p^2 + 2/3 q^2 , (2p^2 - 3q^2) Multiply the following:
  113. (x^2 - 5x + 6), (2x + 7) Multiply the following:
  114. (3x^2 + 5x - 8), (2x^2 - 4x + 3) Multiply the following:
  115. (2x - 2y - 3), (x + y + 5) Multiply the following:
  116. (3x + 2y)^2 + (3x - 2y)^2 Simplify
  117. (3x + 2y)^2 - (3x - 2y)^2 Simplify
  118. (7/9 a + 9/7 b)^2 - ab Simplify
  119. (3/4 x - 4/3 y)^2 + 2xy Simplify
  120. (1.5p + 1.2q)^2 - (1.5p - 1.2q)^2 Simplify
  121. (2.5m + 1.5q)^2 + (2.5m - 1.5q)^2 Simplify
  122. (x^2 - 4) + (x^2 + 4) + 16 Simplify
  123. (ab - c)^2 + 2abc Simplify
  124. (a - b) (a^2 + b^2 + ab) -(a + b) (a^2 + b^2 - ab) Simplify
  125. (b^2 -49)(b + 7) + 343 Simplify
  126. (4.5a + 1.5b)^2 + (4.5b + 1.5a)^2 Simplify
  127. (pq-qr)^2 + 4pq^2 r Simplify
  128. (s^2 t + tq^2)^2 - (2stq)^2 Simplify

Exercise
Question 1.

The product of a monomial and a binomial is a
A. monomial

B. binomial

C. trinomial

D. none of these


Answer:

⇒ Monomial has single term while binomial has two terms.


⇒ Let us suppose a monomial = c and a binomial = (a – b)


⇒ product of ‘c’ and (a – b) are as follows:


⇒ c× (a – b)


= c× a – c× b


= (ca – cb) (This is a binomial)


⇒ Thus we can conclude that product of a monomial and a binomial is binomial.


Option (a) does not match to our solution.


Option (b) does match to our solution.


Option (c) does not match to our solution.


Option (d) does not match to our solution.


So, option (b) is correct answer.


Question 2.

In a polynomial, the exponents of the variables are always
A. integers

B. positive integers

C. non-negative integers

D. non-positive integers


Answer:

⇒ according to definition Polynomial is defined as an expression consisting of variables and coefficients that involves non – negative exponents of variable.


Option (a) does not match to our solution.


Option (b) does not match to our solution.


Option (c) does match to our solution.


Option (d) does not match to our solution.


So, option (c) is correct answer.


Question 3.

Which of the following is correct?
A. (a – b)2 = a2 + 2ab – b2

B. (a – b)2 = a2 - 2ab – b2

C. (a – b)2 = a2 – b2

D. (a + b)2 = a2 + 2ab – b2


Answer:

⇒ (a – b)2 =(a – b)(a – b)


=(a× a – a× b – a× b + b× b)


=(a2 – 2ab + b2)


Option (a) does match to our solution.


Option (b) does not match to our solution.


Option (c) does not match to our solution.


Option (d) does not match to our solution.


So, option (a) is correct answer.


Question 4.

The sum of -7pq and 2pq is
A. -9pq

B. 9 pq

C. 5 pq

D. -5 pq


Answer:

The addition is as follows:


⇒ -7pq + 2pq


=pq(-7 +2)


=pq(-5)


= (-5pq)


⇒ Result is as follows: (-5pq)


Option (a) does not match to our solution.


Option (b) does not match to our solution.


Option (c) does not match to our solution.


Option (d) does match to our solution.


So, option (d) is correct answer.


Question 5.

If we subtract -3x2y2 from x2y2, then we get
A. -4x2y2

B. -2x2y2

C. 2x2y2

D. 4x2y2


Answer:

Subtraction is as follows:


⇒ x2y2 – (-3x2y2)


= x2y2 + 3x2y2


= 4x2y2


The result is as follows: 4x2y2


Option (a) does not match to our solution.


Option (b) does not match to our solution.


Option (c) does not match to our solution.


Option (d) does match to our solution.


So, option (d) is correct answer.


Question 6.

Like term as 4m3n2 is
A. 4m2n2

B. -6m3n2

C. 6pm3n2

D. 4m3n


Answer:

⇒ Like term are the terms which have same variable and powers. The coefficients need not to be matched.


⇒ Here 4m3n2 and – 6m3n2 are like term. Because they have same variables and powers.


Option (a) does not match to our solution.


Option (b) does match to our solution.


Option (c) does not match to our solution.


Option (d) does not match to our solution.


So, option B. is correct answer.


Question 7.

Which of the following is a binomial?
A. 7 × a + a

B. 6a2 + 7b + 2c

C. 4a × 3b × 2c

D. 6 (a2 + b)


Answer:

⇒ A binomial is a polynomial which have two terms.


⇒ in option (a)


⇒ given polynomial = (7× a + a)


=7a +a


=8a


⇒ 8a is monomial.


⇒ in option (b)


⇒ Given polynomial = 6a2 + 7b + 2c


⇒ There are three terms in this polynomial. So, this is a trinomial.


⇒ in option (c)


⇒ Given polynomial = 4a× 3b× 2c


=24abc


⇒ There are one term in this polynomial.


∴ This polynomial is a monomial.


⇒ in option (d)


⇒ Given polynomial = 6(a2 + b)


= 6a2 +6b


⇒ there are two terms in this polynomial.


∴ this polynomial is binomial.


Option (a) does not match to our solution.


Option (b) does not match to our solution.


Option (c) does not match to our solution.


Option (d) does match to our solution.


So, option (d) is correct answer.


Question 8.

Sum of a – b + ab, b + c – bc and c – a – ac is
A. 2c + ab – ac - bc

B. 2c - ab – ac - bc

C. 2c + ab + ac + bc

D. 2c - ab + ac + bc


Answer:

Addition is as follows:


⇒ (a – b + ab)+(b + c – bc)+(c – a – ac)


= (a – b + ab + b + c – bc + c – a – ac)


=(2c + ab – bc – ac)


=(2c + ab – ac – bc)


Option (a) does match to our solution.


Option (b) does not match to our solution.


Option (c) does not match to our solution.


Option (d) does not match to our solution.


So, option (a) is correct answer.


Question 9.

Product of the following monomials 4p, -7q3, -7pq is
A. 196p2q4

B. 196 pq4

C. -196 p2q4

D. 196 p2q2


Answer:

The multiplication is as follows:


⇒ (4p)× (-7q3)× (-7pq)


= (-28pq3)× (-7pq)


= (196p2 q4)


Option (a) does match to our solution.


Option (b) does not match to our solution.


Option (c) does not match to our solution.


Option (d) does not match to our solution.


So, option (a) is correct answer.


Question 10.

Area of a rectangle with length 4ab and breadth 6b2 is
A. 24a2b2

B. 24 ab3

C. 24ab2

D. 24 ab


Answer:

⇒ Area of a rectangle = length× width


⇒ Area of a rectangle = 4ab× 6b2


⇒ Area of a rectangle = 24ab3


Option (a) does not match to our solution.


Option (b) does match to our solution.


Option (c) does not match to our solution.


Option (d) does not match to our solution.


So, option (b) is correct answer.


Question 11.

Volume of a rectangular box (cuboid) with length = 2ab, breadth = 3 ac and height = 2ac is
A. 12a3bc2

B. 12a3bc

C. 12a2bc

D. 2ab + 3ac + 2ac


Answer:

⇒ Volume of rectangular box (cuboid) = length× breadth× height


⇒ Volume of rectangular box (cuboid) = 2ab× 3ac× 2ac


⇒ Volume of rectangular box (cuboid) = 12a3bc2


Option (a) does match to our solution.


Option (b) does not match to our solution.


Option (c) does not match to our solution.


Option (d) does not match to our solution.


So, option (a) is correct answer.


Question 12.

Product of 6a2 – 7b + 5ab and 2ab is
A. 12a3b – 14ab2 + 10ab

B. 12a3b – 14ab2 + 10a2b2

C. 6a2 – 7b + 7 ab

D. 12a2b – 7ab2 + 10ab


Answer:

The multiplication is follows:


⇒ (6a2 – 7b + 5ab) × 2ab


=(6a2× 2ab – 7b× 2ab + 5ab× 2ab)


=(12a3b – 14ab2 + 10 a2b2)


⇒ Result is as follows: (12a3b – 14ab2 + 10 a2b2)


Option (a) does not match to our solution.


Option (b) does match to our solution.


Option (c) does not match to our solution.


Option (d) does not match to our solution.


So, option (b) is correct answer.


Question 13.

Square of 3x – 4y is
A. 9x2 – 16y2

B. 6x2 – 8y2

C. 9x2 + 16y2 + 24xy

D. 9x2 + 16y2 - 24xy


Answer:

⇒ To find square of (3x – 4y) using formula –


⇒ (a – b)2=a2 + b2 – 2ab


⇒ here, a = 3x and b= 4y


⇒ (3x – 4y)2= (3x)2 + (4y)2 – 2× (3x)×(4y)


⇒ (3x – 4y)2= 9x2 + 16y2 – 24xy


Option (a) does not match to our solution.


Option (b) does not match to our solution.


Option (c) does not match to our solution.


Option (d) does match to our solution.


So, option (d) is correct answer.


Question 14.

Which of the following are like terms?
A. 5xyz2, -3xy2z

B. -5xyz2, 7xyz2

C. 5xyz2, 5x2yz

D. 5xyz2, x2y2z2


Answer:

⇒ Like term are the terms which have same variable and powers. The coefficients need not to be matched.


⇒ Here -5xyz2 and 7xyz2 have same variables and same powers.


∴ - 5xyz2 and 7xyz2 are like terms.


Option (a) does not match to our solution.


Option (b) does match to our solution.


Option (c) does not match to our solution.


Option (d) does not match to our solution.


So, option (b) is correct answer.


Question 15.

Coefficient of y in the term is
A. -1

B. -3

C.

D.


Answer:

⇒ As we know that coefficients are the numbers which multiplies the variables.


⇒ In the given term , we can see that ‘y’ is a variable and is a constant which multiplies variable ‘y’.


⇒ In mathematical form –



Option (a) does not match to our solution.


Option (b) does not match to our solution.


Option (c) does match to our solution.


Option (d) does not match to our solution.


So, option (c) is correct answer.


Question 16.

a2 – b2 is equal to
A. (a – b)2

B. (a – b) (a – b)

C. (a + b) (a – b)

D. (a + b) (a + b)


Answer:

⇒ Solving option (a)


⇒ (a – b)2 = (a – b)× (a – b)


⇒ =(a× a – a× b – b× a + b× b)


=(a2 – 2ab + b2)


⇒ Solving option (b)


⇒ (a – b)(a – b) = (a× a – a× b – b× a + b× b)


⇒ =(a2 – 2ab + b2)


⇒ Solving equation (c)


⇒ (a + b)(a – b) = (a× a – a× b + b× a – b× b)


⇒ = (a2 – b2)


⇒ Solving option (d)


⇒ (a + b)(a + b) = (a× a + a× b + b× a + b× b)


⇒ = (a2 +2ab + b2)


Option (a) does not match to our solution.


Option (b) does match to our solution.


Option (c) does not match to our solution.


Option (d) does not match to our solution.


So, option (b) is correct answer.


Question 17.

Common factor of 17 abc, 34ab2, 51a2b is
A. 17abc

B. 17 ab

C. 17 ac

D. 17a2b2c


Answer:

⇒ Factorise the given terms


⇒ 17 abc = 17× a× b× c


⇒ 34 ab = 17× 2× a× b× b


⇒ 51ab = 17× 3× a× a× b


⇒ Common factor = 17× a× b


⇒ Common factor = 17ab


Option (a) does not match to our solution.


Option (b) does match to our solution.


Option (c) does not match to our solution.


Option (d) does not match to our solution.


So, option (b) is correct answer.


Question 18.

Square of 9x – 7xy is
A. 81x2 + 49x2y2

B. 81x2 - 49x2y2

C. 81x2 + 49x2y2- 126x2y

D. 81x2 + 49x2y2- 63x2y


Answer:

⇒ Applying formula


⇒ (a – b)2 = a2 + b2 – 2ab


⇒ square of (9x – 7xy) means (9x – 7xy)2


⇒ Here, a = 9x and b = 7xy


⇒ (9x – 7xy)2 = (9x) + (7xy) – 2×(9x)×(7xy)


⇒ (9x – 7xy)2 = 81x2 + 49x2y2 – 126x2y


Option (a) does not match to our solution.


Option (b) does not match to our solution.


Option (c) does match to our solution.


Option (d) does not match to our solution.


So, option (c) is correct answer.


Question 19.

Factorised form of 23xy – 46x + 54y – 108 is
A. (23x + 54) (y – 2)
B. (23x + 54y) (y – 2)
C. (23xy + 54y) (-46x – 108)
D. (23x + 54) (y + 2)


Answer:

lets write factorise form of 23xy – 46x + 54y – 108


⇒ 23xy – 46x + 54y – 108 = 23x(y – 2) + 54(y – 2)
Taking (y-2) as common from the term, we get,


= (y – 2)(23x + 54)


= (23x + 54)(y – 2)


Hence, option (a) is correct


Question 20.

Factorised form of r2 -10r + 21 is
A. (r-1)(r-4)

B. (r-7)(r-3)

C. (r-7)(r+3)

D. (r+7)(r+3)


Answer:

⇒ Factorise form will be as follows:


⇒ (r2 -10r + 21) = r – (7+3)r + 21


⇒ (r2 -10r + 21) = r – 7r – 3r + 21


⇒ (r2 -10r + 21) = r(r – 7) – 3(r – 7)


⇒ (r2 -10r + 21) = (r – 7)(r – 3)


Option (a) does not match to our solution.


Option (b) does match to our solution.


Option (c) does not match to our solution.


Option (d) does not match to our solution.


So, option (b) is correct answer.


Question 21.

Factorised form of p2 – 17p – 38 is
A. (p-19) (p+2)

B. (p-19) (p-2)

C. (p+19) (p+2)

D. (p+19) (p-2)


Answer:

We have,




(By splitting the middle term, so that the product of their numerical coefficients is equal constant term)


=p(p-19)+2(p-19)


=(p-19)(p+2)


(Because )


Question 22.

On dividing 57p2qr by 114pq, we get
A. pr

B. pr

C. pr

D. 2 pr


Answer:

Required value




Question 23.

On dividing p (4p2 – 16) by 4p (p – 2), we get
A. 2p+4

B. 2p-4

C. p+2

D. p-2


Answer:

We have,




(Because )





Question 24.

The common factor of 3ab and 2cd is
A. 1

B. -1

C. a

D. c


Answer:

We have monomials 3ab and 2cd


Now,



We see that, there is no common factor between them except 1


(Neither numerical nor letter)


Question 25.

An irreducible factor of 24x2y2 is
A. x2

B. y2

C. x

D. 24x


Answer:

A factor is said to be irreducible, if it cannot be factorised further


We have, 24x2y2 = 2×2×2×3×x×x×y×y


Hence, an irreducible factor of is


Question 26.

Number of factors of (a + b)2 is
A. 4

B. 3

C. 2

D. 1


Answer:

We can write as and this cannot be


Factorised further.


Hence, number of factors of is 2


Question 27.

The factorised form of 3x – 24 is
A. 3x × 24

B. 3 (x – 8)

C. 24 (x – 3)

D. 3 (x – 12)


Answer:



(Taking 3 as common)


Question 28.

The factors of x2 – 4 are
A. (x – 2), (x – 2)

B. (x + 2), (x – 2)

C. (x + 2), (x + 2)

D. (x – 4), (x – 4)


Answer:



(Because )


Hence, , are factors of


Question 29.

The value of (-27x2y) ÷ (-9xy) is
A. 3xy

B. -3xy

C. -3x

D. 3x


Answer:

We have,




=3x


Question 30.

The value of (3x3 + 9x2 + 27x) ÷ 3x is
A. 2a + 2b

B. 2a - 2b

C. 2a2 + 2b2

D. 2a2 - 2b2


Answer:



Question 31.

The value of (3x3 +9x2 + 27x) ÷ 3x is

(a) x2 +9 + 27x (b) 3x3 +3x2 + 27x

(c) 3x3 +9x2 + 9 (d) x2 +3x + 9


Answer:

(d)

Given: (3x3 +9x2 + 27x) ÷ 3x




= x2 + 3x + 9



Question 32.

The value of (a + b)2 + (a – b)2 is:

(a) 2a + 2b (b) 2a – 2b (c) 2a2 + 2b2 (d) 2a2 – 2b2


Answer:

C

Given:


(a + b)2 + (a – b)2


⇒ a2 + b2 + 2ab + a2 + b2 – 2ab


⇒ 2a2 + 2b2



Question 33.

The value of (a + b)2 – (a – b)2 is

(a) 4ab (b) – 4ab (c) 2a2 + 2b2 (d) 2a2 – 2b2


Answer:

(a + b)2 - (a – b)2


⇒ a2 + b2 + 2ab - a2 - b2 + 2ab


⇒ 4ab



Question 34.

Fill in the blanks to make the statements true:

The product of two terms with like signs is a………… term.


Answer:

Positive

If both like terms are either positive or negative, then the resultant term will always be positive.



Question 35.

Fill in the blanks to make the statements true:

The product of two terms with unlike signs is a …………….. term.


Answer:

Negative

As the product of a positive term and a negative term is always negative.



Question 36.

Fill in the blanks to make the statements true:

a (b + c) = ax ……….. × ax ……….. .


Answer:

b,c

We have,



(Using left distributive law => The law relating the operations of multiplication and addition, stated symbolically, a(b+c)=ab+ac; that is, the monomial facto a is distributed, or separately applied, to each term of the binomial factor b+c, resulting in the product ab+ac. From this law it is easy to show that the result of first adding several numbers and then multiplying each separately by the number and then adding the products)



Question 37.

Fill in the blanks to make the statements true:

(a – b) …………….. = a2 – 2ab + b2


Answer:

(a-b)

We know that,



(Because )



Question 38.

Fill in the blanks to make the statements true:

a2 – b2 = (a + b) …………… .


Answer:

(a-b)

We have,


(Because )


Alternative method


Let




Question 39.

Fill in the blanks to make the statements true:

(a – b)2 + ……….. = a2 – b2


Answer:


Let



(Because )






Question 40.

Fill in the blanks to make the statements true:

(a + b)2 - 2ab = ……… + ……… .


Answer:


We have,



(Because )




Question 41.

Fill in the blanks to make the statements true:

(x + a) (x + b) = x2 + (a + b)x + ……….. .


Answer:

ab





Question 42.

Fill in the blanks to make the statements true:

The product of two polynomials is a ………. .


Answer:

polynomial

An expression containing one or more terms with non-zero coefficient, with variables having non-negative exponents, is called a polynomial. When we multiply two polynomials, the coefficients of the terms get multiplied and the power of the variables get added. This gives us the resulting answer as a polynomial, too.



Question 43.

Fill in the blanks to make the statements true:

Common factor of ax2 + bx is ……….. .


Answer:

x



In both of the above terms, the common factor is .



Question 44.

Fill in the blanks to make the statements true:

Factorised form of 18mn + 10mnp is ……… .


Answer:

2mn(9 + 5p)

The irreducible factors of 18mn and 10mnp are


18mn = 2×3×3×m×n


10mnp = 2×5×m×n×p


Here, the common factors of the two terms are 2mn. So the factorization of 18mn + 10mnp will be


18mn + 10mnp = (2×3×3×m×n) + (2×5×m×n×p)


= (2mn×9) + (2mn×5p)


= 2mn(9 + 5p)



Question 45.

Fill in the blanks to make the statements true:

Factorised form of 4y2 – 12y + 9 is ……… .


Answer:

(2y - 3)2

Here, the polynomial has three terms where the first and the last term are perfect squares with a negative sign of the middle term. So it is of the form where a = 2y and b = 3 such that




Now, we know that


Comparing with this, we get,




Question 46.

Fill in the blanks to make the statements true:

38x3y2z÷ 19xy2 is equal to ………. .


Answer:

2x2z

While dividing two monomials, the coefficient of the dividend is divided by the coefficient of the divisor whereas the variables of the dividend are divided by the variables of the divisor.


Here, dividend =


divisor =


So,



Hence, the answer is



Question 47.

Fill in the blanks to make the statements true:

Volume of a rectangular box with length 2x, breadth 3y and height 4z is ……………. .


Answer:

24xyz

given:- length of box = 2x


breadth of box = 3y


height of box = 4z


Volume of rectangular box = length × breadth × height


= (2x) × (3y) × (4z)


= 24xyz



Question 48.

Fill in the blanks to make the statements true:

672 – 372 = (67 – 37) × ……………. = ………… .


Answer:

(67 + 37), 3120

672 – 372 is of the form a2 – b2. Comparing the two we get, a = 67 and b = 37.


We have a2 - b2 = (a + b)(a-b).


So, 672 – 372 = (67 + 37)(67-37)


= (104)(30)


= 104×30 = 3120



Question 49.

Fill in the blanks to make the statements true:

1032 – 1022 = ………….. × (103 – 102) = ……… .


Answer:

(103 + 102), 205

1032 – 1022 is of the form a2 – b2. Comparing the two we get, a = 103 and b = 102.


We have a2 - b2 = (a + b)(a-b).


So, 1032 – 1022 = (103 + 102)(103-102)


= (205)(1)


= 205×1 = 205



Question 50.

Fill in the blanks to make the statements true:

Area of a rectangular plot with side 4x2 and 3y2 is ……….. .


Answer:

12x2y2

Let the length of rectangular plot = l = 4x2


The breadth of rectangular plot = b = 3y2


Area of rectangular plot = l×b


= 4x2 × 3y2


= 12x2y2



Question 51.

Fill in the blanks to make the statements true:

Volume of a rectangular box with l = b = h = 2x is …………. .


Answer:

8x3

Given:- l = b = h = 2x


Volume of rectangular plot = l×b×h


= 2x × 2x × 2x


= 8x3



Question 52.

Fill in the blanks to make the statements true:

The coefficient in – 37abc is …………. .


Answer:

-37

The numerical factor of a term is called its coefficient. Here, the numerical factor is -37.



Question 53.

Fill in the blanks to make the statements true:

Number of terms in the expression a2 + bc ×d is ……………. .


Answer:

two

The expression can be written as


A2 + bc×d = a2 + bcd


The multiplication sign does not mean that there are two separate terms. Two terms can be separated only by the operations of addition or subtraction.



Question 54.

Fill in the blanks to make the statements true:

The sum of areas of two squares with sides 4a and 4b is ………………. .


Answer:

16(a2 + b2)

Given:- side of first square = 4a


⇒ Area of first square = (side)2


= (4a)2


= 16a2


side of second square = 4b


⇒ Area of second square = (side)2


= (4b)2


= 16b2


Sum of areas of the two squares = 16a2 + 16b2


= 16(a2 + b2)



Question 55.

Fill in the blanks to make the statements true:

The common factor method of factorisation for a polynomial is based on ………….. property.


Answer:

distributive



Question 56.

Fill in the blanks to make the statements true:

The side of the square of area 9y2 is ………. .


Answer:

3y

Area of a square = (side)2


⇒ 9y2 = (side)2


Taking square root on both sides, we get,


side =


To find the square root of a monomial, we find the square roots of the coefficient and variables separately.


Now, 9y2 = (3y)2


Thus, side of square = 3y



Question 57.

Fill in the blanks to make the statements true:

On simplification = …….. .


Answer:


We have,





Question 58.

Fill in the blanks to make the statements true:

The factorisation of 2x + 4y is ………. .


Answer:

2(x + 2y)

2x + 4y = (2×x) + (2×2×y)


= (2×x) + (2×2y)


= 2(x + 2y)



Question 59.

State whether the statements are true (T) or false (F).

(a + b)2 = a2 + b2


Answer:

Lets recall the formula of (a + b)2.

(a + b)2 = a2 + 2×a×b + b2


⇒ (a + b)2 = a2 + 2ab + b2


But right-hand side of the equation does not match left-hand side of the equation.


That is,


a2 + 2ab + b2 ≠ a2 + b2


⇒ (a + b)2 ≠ a2 + b2


Hence, this statement is false.



Question 60.

State whether the statements are true (T) or false (F).

(a - b)2 = a2 - b2


Answer:

Expansion of (a – b)2 is,

(a – b)2 = a2 – 2×a×b + b2


⇒ (a – b)2 = a2 – 2ab + b2


And a2 – 2ab + b2 ≠ a2 – b2


⇒ (a – b)2 ≠ a2 – b2


Hence, this statement is false.



Question 61.

State whether the statements are true (T) or false (F).

(a + b) (a – b) = a2 – b2


Answer:

Let us expand (a + b)(a – b).

Multiply each term with the other term which is in multiplication with it.


(a + b)(a – b) = a2 – ab + ab – b2


⇒ (a + b)(a – b) = a2 +(ab – ab) – b2


⇒ (a + b)(a – b) = a2 + 0 – b2


⇒ (a + b)(a – b) = a2 – b2


Hence, this statement is true.



Question 62.

State whether the statements are true (T) or false (F).

The product of two negative terms is a negative term.


Answer:

Let us understand this by an example.

Let two negative terms be -a and -b.


Multiplying these two negative terms.


-a × -b = (-1) × (-1) × ab


⇒ -a × -b = +1 × ab [∵, -1 × -1 = 1]


⇒ -a × -b = +ab


The product of -a and -b came out to be ab (positive term).


Whenever two negative terms are multiplied, the product is always positive as the two negatives forms a positive.


Hence, this statement is false.



Question 63.

State whether the statements are true (T) or false (F).

The product of one negative and one positive term is a negative term.


Answer:

Let us understand this by an example.

Let a negative and a positive term be -a and b respectively.


Then, multiply these two terms.


-a × b = (-1) × (+1) × ab


⇒ -a × b = -1 × ab [∵, -1 × 1 = -1]


⇒ -a × b = -ab


Similarly, take any pair of such numbers, we will always get a negative term as a negative number multiplied by a positive number always gives negative number.


Hence, this statement is true.



Question 64.

State whether the statements are true (T) or false (F).

The coefficient of the term -6x2y2 is -6.


Answer:

Coefficient is a numerical or constant quantity placed before and multiplying the variable in an algebraic expression.

The algebraic expression in -6x2y2 is x2y2.


And the constant term before x2y2 is -6.


Thus, coefficient of the term -6x2y2 is -6.


Hence, the statement is true.



Question 65.

State whether the statements are true (T) or false (F).

p2q + r2r + r2q is a binomial.


Answer:

An algebraic expression which consists of two non-zero terms is called a binomial.

Observe in the given question, there are three non-zero terms, namely


p2q, r2r and r2q.


Thus, this is a polynomial having three terms, not a binomial.


Hence, the statement is false.



Question 66.

State whether the statements are true (T) or false (F).

The factors of a2 – 2ab + b2 are (a+b) and (a+b).


Answer:

Lets factorize a2 – 2ab + b2 by splitting middle term.

a2 – 2ab + b2 = a2 – ab – ab + b2 [∵, -ab – ab = - 2ab & (-ab)(-ab) = a2b2]


⇒ a2 – 2ab + b2 = a(a – b) – b(a – b)


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


So, the factors of a2 – 2ab + b2 are (a – b) and (a – b).


Hence, the statement is false.



Question 67.

State whether the statements are true (T) or false (F).

h is a factor of 2π (h+r).


Answer:

Factorizing 2π (h + r), we get

2π (h + r) = 2π × (h + r)


⇒ There are three factors of 2π (h + r) namely, 2, π and (h + r).


But h is not any factor of 2π (h + r).


Hence, the statement is false.



Question 68.

State whether the statements are true (T) or false (F).

Some of the factors of are , , n and (n+1).


Answer:

Factorizing n2/2 + n/2, by simply taking out common variables and constants.

n2/2 + n/2 = n2×1/2 + n×1/2


⇒ n2/2 + n/2 = 1/2 (n×n + n) = 1/2 n (n + 1)


⇒ 1/2, n and (n + 1) are factors of n2/2 + n/2.


Hence, the statement is true.



Question 69.

State whether the statements are true (T) or false (F).

An equation is true for all values of its variables.


Answer:

An equation is a statement of equality between two quantities or algebraic expressions. Most algebraic equations are TRUE when certain values are substituted for the variable (such as x) and are FALSE for all other values. The values that make equations TRUE are called "solutions". So, an equation is not necessarily true for all values of its variables.

Hence, the statement is false.



Question 70.

State whether the statements are true (T) or false (F).

x2 + (a+b)x + ab = (a+b) (x+ab)


Answer:

We need to factorize x2 + (a + b)x + ab, by splitting the middle term:

x2 + (a + b)x + ab = x2 + ax + bx + ab [∵, ax + bx = (a + b)x & ax × bx = abx2)


⇒ x2 + (a + b)x + ab = x(x + a) + b(x + a)


⇒ x2 + (a + b)x + ab = (x + a)(x + b)


And (x + a)(x + b) ≠ (a + b)(x + ab)


⇒ x2 + (a + b)x + ab ≠ (a + b)(x + ab)


Hence, the statement is false.



Question 71.

State whether the statements are true (T) or false (F).

Common factor of 11pq2, 121p2q3, 1331p2q is 11p2q2.


Answer:

Common factors of 11pq2, 121p2q3 and 1331p2q can be found out as:

Common factors (11pq2, 121p2q3, 1331p2q) = Common factors (11×pq, 11×11p2q3, 11×121p2q)


⇒ Common factors (11pq2, 121p2q3, 1331p2q) = 11


[∵, 11 divides all the three term 11pq2, 121p2q3 and 1331p2q; p divides all the three terms 11pq2, 121p2q3 and 1331p2q; and q divides all the three terms 11pq2, 121p2q3 and 1331p2q]


Hence, the statement is false.



Question 72.

State whether the statements are true (T) or false (F).

Common factor of 12a2b2+4ab2-32 is 4.


Answer:

Let us consider that common factor of 12a2b2 + 4ab2 – 32 = 4

Check: 12a2b2 + 4ab2 – 32 = 4 (3a2b2 + ab2 – 8)


Notice, there are no further common factor in the equation.


Thus, common factor of 12a2b2 + 4ab2 – 32 is 4.


Hence, the statement is true.



Question 73.

State whether the statements are true (T) or false (F).

Factorisation of -3a2+3ab+3ac is 3a(-a–b –c).


Answer:

Let us factorize -3a2 + 3ab + 3ac.

-3a2 + 3ab + 3ac = 3(-a×a + a×b + a×c)


⇒ -3a2 + 3ab + 3ac = 3a (-a + b + c)


But, 3a (-a + b + c) ≠ 3a (-a – b – c)


Hence, the statement is false.



Question 74.

State whether the statements are true (T) or false (F).

Factorised form of p2+30p+216 is (p+18) (p-12).


Answer:

Factorizing the equation p2 + 30p + 216, by splitting the middle term of the equation:

p2 + 30p + 216 = p2 + 18p + 12p + 216 [∵, (18p + 12p) = 30p & (18p × 12p) = 216p2)


⇒ p2 + 30p + 216 = p (p + 18) + 12 (p + 18)


⇒ p2 + 30p + 216 = (p + 12) (p + 18)


But, (p + 12)(p + 18) ≠ (p + 18)(p – 12)


Hence, the statement is false.



Question 75.

State whether the statements are true (T) or false (F).

The difference of the squares of two consecutive numbers is their sum.


Answer:

Let two consecutive numbers be x and (x + 1).

Then square of these numbers are x2 and (x + 1)2.


Difference of squares of these consecutive numbers = (x + 1)2 – x2


= x2 + 1 + 2x – x2 [∵, (a + b)2 = a2 + b2 + 2ab)


= 2x + 1


= x + x + 1


= (x) + (x + 1)


= sum of the two consecutive numbers x and x+1


Thus, difference of squares of two consecutive numbers = sum of the same consecutive numbers.


Hence, the statement is true.



Question 76.

State whether the statements are true (T) or false (F).

abc + bca + cab is a monomial.


Answer:

An algebraic expression which consists of one non-zero terms is called a monomial.

Observe in the given question, there are three non-zero terms, namely


abc, bca and cab.


Thus, this is a polynomial having three terms, not a monomial.


Hence, the statement is false.



Question 77.

State whether the statements are true (T) or false (F).

On dividing by, the quotient is 9.


Answer:

Divide p/3 by 3/p, we get

p/3 ÷ 3/p = p/3 × p/3 = p2/9


And p2/9 ≠ 9.


⇒ the quotient is p2/9, not 9.


Hence, the statement is false.



Question 78.

State whether the statements are true (T) or false (F).

The value of p for 512 – 492 = 100p is 2.


Answer:

Solving for p,

(51)2 – (49)2 = 100p


⇒ (50 + 1)2 – (50 – 1)2 = 100p [∵, 51 = 50 + 1 & 49 = 50 – 1]


⇒ (2500 + 1 + 100) – (2500 + 1 – 100) = 100p [∵, (a + b)2 = a2 + b2 + 2ab and (a – b)2 = a2 + b2 – 2ab)


⇒ 2500 + 1 + 100 – 2500 – 1 + 100 = 100p


⇒ 200 = 100p


⇒ 100p = 200


⇒ p = 200/100 = 2


The value of p is 2.


Hence, the statement is true.



Question 79.

State whether the statements are true (T) or false (F).

(9x – 51) ÷ 9 is x – 51.


Answer:

Solving (9x – 51) ÷ 9,

(9x – 51) ÷ 9 = (9x – 51)/9


9 divides the term 9x but does not divide 51.


So, the answer comes out to be (9x – 51)/9.


(9x – 51)/9 ≠ x – 51


Hence, the statement is false.



Question 80.

State whether the statements are true (T) or false (F).

The value of (a+1) (a-1) (a2+1) is a4-1


Answer:

Solving it, we get

(a + 1)(a – 1)(a2 + 1) = {(a + 1)(a – 1)} × (a2 + 1)


⇒ (a + 1)(a – 1)(a2 + 1) = (a2 – 1)(a2 + 1)


[∵, (x + y)(x – y) = x2 – y2; Put x = a and y = 1 ⇒ (a + 1)(a – 1) = a2 – 1]


⇒ (a + 1)(a – 1)(a2 + 1) = a4 – 1


[∵, (x2 + y2)(x2 – y2) = x4 – y4; Put x = a and y = 1 ⇒ (a2 + 1)(a2 – 1) = a4 – 1]


Thus, the value of (a + 1)(a – 1)(a2 + 1) is a4 – 1.


Hence, the statement is true.



Question 81.

Add:

7a2bc, -3abc2, 3a2bc, 2abc2


Answer:

The addition is as follows:


The result is as follows 10a2bc – abc2



Question 82.

Add:

9ax, + 3by – cz, -5by + ax + 3cz


Answer:

The addition is as follows:


The result is as follows 10ax-2by + 2cz



Question 83.

Add:

xy2z2 + 3x2y2z–4x2yz2,-9x2y2z + 3xy2z2 + x2yz2


Answer:

The addition is as follows:


The result is as follows 4xy2z2-6x2y2z-3x2yz2



Question 84.

Add:

5x2 – 3xy + 4y2 – 9, 7y2 + 5xy – 2x2 + 13


Answer:

: The addition is as follows:


The result is as follows 7x2 + 2xy + 11y2 + 4



Question 85.

Add:

2p4 – 3p3 + p2 – 5p + 7, -3p4-7p3-3p2-p-12


Answer:

The addition is as follows:


The result is as follows -p4-4p3-2p2-6p-5



Question 86.

Add:
3a(a-b-c), 2b (a-b + c)


Answer:

To find: 3a(a - b - c) + 2b(a - b + c)
The addition is as follows:

Here,
3a(a - b - c) = 3a2 - 3ab - 3ac


2b(a - b + c) = 2ab - 2b2 + 2bc


Hence the two polynomials to be added are 3a2 - 3ab - 3ac and 2ab - 2b2 + 2bc


3a(a - b - c) + 2b(a - b + c) = 3a2 - 3ab - 3ac + 2ab - 2b2 + 2bc = 3a2 - ab - 3ac + 2bc - 2b2


The result is as follows: 3a2 - ab - 3ac + 2bc - 2b2


Question 87.

Add:

3a (2b + 5c), 3c (2a + 2b)


Answer:

Here, 3a(2b + 5c) = 6ab + 15ac

3c(2a + 2b) = 6ac + 6bc


Hence the two polynomials to be added are 6ab + 15ac and


6ac + 6bc



The result is as follows 6ab + 21ac + 6bc



Question 88.

Subtract:

5a2b2c2 from -7a2b2c2


Answer:

The subtraction is as follows:


The result is as follows:- 12a2b2c2



Question 89.

Subtract:

6x2 – 4xy + 5y2 from 8y2 + 6xy – 3x2


Answer:

The subtraction is as follows:

We can also write 8y2 + 6xy – 3x2 as -3x2 + 6xy + 8y2


Therefore,



The result is as follows: -9x2 + 10xy + 3y2



Question 90.

Subtract:

2a2b2c2 + 4a2b2c - 5a2bc2 from -10a2b2c + 4ab2c2 + 2a2bc2


Answer:

The subtraction is as follows:


The result is as follows: -14a2b2c + 4ab2c2 + 7a2bc2-2a2b2c2



Question 91.

Subtract:

3t4–4t3 + 2t2–6t + 6 from -4t4 + 8t3-4t2-2t + 11


Answer:

The subtraction is as follows:


The result is as follows: -7t4 + 12t3-6t2 + 4t + 5



Question 92.

Subtract:

2ab + 5bc–7ac from 5ab–2bc–2ac + 10abc


Answer:

The subtraction is as follows:


The result is as follows: 3ab -7bc + 5ac + 10abc



Question 93.

Subtract:

7p (3q + 7p) from 8p (2p -7q)


Answer:

The subtraction is as follows:

Here 8p(2p-7q) = 16p2-56pq and


7p(3q + 7p) = 21pq + 49p2


Therefore,



The result is as follows: -33p2-77pq



Question 94.

Subtract:

-3p2 + 3pq + 3px from 3p (-p-a-r)


Answer:

The subtraction is as follows:

Here,3p(-p-a-r) = -3p2-3pa-3pr


Therefore,



The result is as follows: 0p2-3pa-3pr-3pq-3px or -3pa-3pr-3pq-3px


Or -3p(a + r + q + x).



Question 95.

Multiply the following:

-7pq2r3, -13p3q2r


Answer:

The multiplication is as follows:

(-7pq2r3) ×(-13p3q2r)


= (-7×-13×3)×(pq2r3.pq2r)(Here dot implies multiplication)


= (273)×(p2q4r4)


= 273p4q4r4


The product is = 273p4q4r4



Question 96.

Multiply the following:

3x2y2z2, 17xyz


Answer:

The multiplication is as follows:

(3x2y2z2)×(17xyz)


= (3×17)×(x2 y2z2.xyz)


= 51x3y3z3


The product is = 51x3y3z3



Question 97.

Multiply the following:

15xy2, 17yz2


Answer:

The multiplication is as follows:

(15xy2)×(17yz2)


= (15×17)×(xy2.yz2)


= 255xy3z2


The product is = 255xy3z2



Question 98.

Multiply the following:

-5a2bc, 11ab, 12abc2


Answer:

The multiplication is as follows:

(-5a2bc)×(11ab)×(12abc2)


= (-5×11×12)(a2bc.ab.abc2)


= -660a4b3c3


The product is = 255xy3z2



Question 99.

Multiply the following:

-3x2y, (5y - xy)


Answer:

The multiplication is as follows:

(-3x2y)×(5y-xy)


= (-3x2y.5y) + (3x2y.xy)


= -15x2y2 + 3x3y2


The product is = -15x2y2 + 3x3y2



Question 100.

Multiply the following:

abc, (bc + ca)

The multiplication is as follows:

(vii) 7prq, (p - q + r)


Answer:

The multiplication is as follows:

(7prq)×(p-q + r)


= (7prq.p-7prq.q + 7prq.r)


= 7p2rq-7prq2 + 7pr2q


The product is = 7p2rq-7prq2 + 7pr2q



Question 101.

Multiply the following:

x2y2z2, (xy – yz + zx)


Answer:

The multiplication is as follows:

(x2y2z2)(xy-yz + zx)


= (x2y2z2.xy-x2y2z2.yz + x2y2z2.zx)


= x3y3z2-x2y3z3 + x3y2z3


The product is = x3y3z2-x2y3z3 + x3y2z3



Question 102.

Multiply the following:

(p + 6), (q – 7)


Answer:

The multiplication is as follows:

(p + 6)×(q-7)


= (p.q-7p + 6q-42)


= pq-7p + 6q-42


The product is = pq-7p + 6q-42



Question 103.

Multiply the following:

6mn, 0mn


Answer:

The multiplication is as follows:

6mn×0mn


= (6×0)mn = 0


The product is = 0



Question 104.

Multiply the following:

a, a5, a6


Answer:

The multiplication is as follows:

a×a5×a6


= a12


The product is = a12



Question 105.

Multiply the following:

b3, 3b2, 7ab5


Answer:

The multiplication is as follows:

b3×3b2×7ab5


= 21ab10


The product is = 21ab10



Question 106.

Multiply the following:

-7st, -1, -12st2


Answer:

The multiplication is as follows:

-7st×-1×-12st2


= -84s2t3


The product is = -84s2t3



Question 107.

Multiply the following:

rs; r3s2


Answer:

The multiplication is as follows:


= ()


=


The product is =



Question 108.

Multiply the following:

(a2 - b2), (a2 + b2)


Answer:

The multiplication is as follows:

(a2-b2)×(a2 + b2)


= (a2.a2 + a2.b2-b2.a2-b2.b2)


= a4 + a2b2-a2b2-b4


= a4 + 0-b4


= a4-b4


The product is = a4-b4



Question 109.

Multiply the following:

(ab + c), (ab + c)


Answer:

The multiplication is as follows:

(ab + c)×(ab + c)


= (ab.ab + ab.c + ab.c + c.c)


= a2b2 + 2abc + c2


The product is = a2b2 + 2abc + c2



Question 110.

Multiply the following:

(pq- 2r), (pq- 2r)


Answer:

The multiplication is as follows:

(pq-2r)×(pq-2r)


= (pq.pq-2pq.r-2pq.r + 2r.2r)


= p2q2-4pqr + 2r2


The product is = p2q2-4pqr + 2r2



Question 111.

Multiply the following:



Answer:

The multiplication is as follows:


=


=


= (Here we have calculated the LCM )


=


The product is =



Question 112.

Multiply the following:

, (2p2 – 3q2)


Answer:

The multiplication is as follows:


=


=


=


=


The product is =



Question 113.

Multiply the following:

(x2 – 5x + 6), (2x + 7)


Answer:

The multiplication is as follows:

(x2-5x + 6)×(2x + 7)


= (x2.2x + 7x2-5x.2x-5x.7 + 6.2x + 6.7)


= 2x3 + 7x2-10x2-35x + 12x + 42


= 2x3-3x2-23x + 42


The product is = 2x3-3x2-23x + 42



Question 114.

Multiply the following:

(3x2 + 5x - 8), (2x2 – 4x + 3)


Answer:

The multiplication is as follows:

(3x2 + 5x-8)×(2x2-4x + 3)


= 3x2.2x2-4x.3x2 + 3x2.3 + 5x.2x2-4x.5x + 5x.3-8.2x2 + 8.4x-8.3


= 6x4-12x3 + 9x3 + 10x3-20x2 + 15x-16x2 + 32x-24


= 6x4 + 7x3-36x2 + 47x-24


The product is = 6x4 + 7x3-36x2 + 47x-24



Question 115.

Multiply the following:

(2x – 2y - 3), (x + y + 5)


Answer:

The multiplication is as follows:

(2x-2y-3)×(x + y + 5)


= 2x.x + 2x.y + 2x.5-2y.x-2y.y-2y.5-3.x-3.y-3.5


= 2x2 + 2xy + 10x-2xy-2y2-10y-3x-3y-15


= 2x2-2y2 + 7x-7y-15


The product is = 2x2-2y2 + 7x-7y-15



Question 116.

Simplify

(3x + 2y)2 + (3x – 2y)2


Answer:

The given expression is (3x + 2y)2 + (3x – 2y)2

We have,


(3x + 2y)2 = (3x)2 + 2.3x.2y + (2y)2(Here we apply standard identities)


= 9x2 + 12xy + 4y2


and


(3x-2y)2 = (3x)2-2.3x.2y + (2y)2


= 9x2-12xy + 4y2


Therefore,


(3x + 2y)2 + (3x – 2y)2 = 9x2 + 12xy + 4y2 + 9x2-12xy + 4y2


= 18x2 + 8y2


= 2(9x2 + 4y2)



Question 117.

Simplify

(3x + 2y)2 - (3x – 2y)2


Answer:

The given expression is (3x + 2y)2 - (3x – 2y)2

We have,


(3x + 2y)2 = (3x)2 + 2.3x.2y + (2y)2


= 9x2 + 12xy + 4y2


and


(3x-2y)2 = (3x)2-2.3x.2y + (2y)2


= 9x2-12xy + 4y2


Therefore,


(3x + 2y)2 - (3x – 2y)2 = 9x2 + 12xy + 4y2-9x2 + 12xy-4y2


= 24xy



Question 118.

Simplify

- ab


Answer:

The given expression is -ab

= -ab


=


Therefore, - ab =



Question 119.

Simplify

+ 2xy


Answer:

The given expression is


+ 2xy


= + 2xy


= + 2xy


=


Therefore, + 2xy =



Question 120.

Simplify

(1.5p + 1.2q)2 – (1.5p - 1.2q)2


Answer:

The given expression is

(1.5p + 1.2q)2 – (1.5p - 1.2q)2


We have


(1.5p + 1.2q)2 = (1.5p)2 + 2(1.5p)(1.2q) + (1.2q)2


and


(1.5p - 1.2q)2 = (1.5p)2-2(1.5p)(1.2q) + (1.2q)2


Therefore,


(1.5p + 1.2q)2 – (1.5p - 1.2q)2


= (1.5p)2 + 2(1.5p)(1.2q) + (1.2q)2-(1.5p)2 + 2(1.5p)(1.2q)-(1.2q)2


= 2(1.5p)(1.2q)



Question 121.

Simplify

(2.5m + 1.5q)2 + (2.5m - 1.5q)2


Answer:

The given expression is

(2.5m + 1.5q)2 + (2.5m - 1.5q)2


We have


(2.5m + 1.5q)2 = (2.5m)2 + 2(2.5m)(1.5q) + (1.5q)2


(2.5m - 1.5q)2 = (2.5m)2-2(2.5m)(1.5q) + (1.5q)2


Therefore,


(2.5m + 1.5q)2 + (2.5m - 1.5q)2


= (2.5m)2 + 2(2.5m)(1.5q) + (1.5q)2 + (2.5m)2-2(2.5m)(1.5q) + (1.5q)2


= 12.50m2 + 4.50q2



Question 122.

Simplify

(x2 - 4) + (x2 + 4) + 16


Answer:

The given expression is

(x2 - 4) + (x2 + 4) + 16


= 2x2 + 16


Therefore, (x2 - 4) + (x2 + 4) + 16 = 2x2 + 16



Question 123.

Simplify

(ab - c)2 + 2abc


Answer:

The given expression is

(ab - c)2 + 2abc


= (ab)2-2(ab)(c) + (c)2 + 2abc


= a2b2-2abc + c2 + 2abc


= a2b2 + c2


Therefore, (ab - c)2 + 2abc = a2b2 + c2



Question 124.

Simplify
(a - b) (a2 + b2 + ab) -(a + b) (a2 + b2 - ab)


Answer:

The given expression is

(a - b) (a2 + b2 + ab) -(a + b) (a2 + b2 - ab)


= (a.a2 + a.b2 + a.ab-b.a2-b.b2-b.ab)-(a.a2 + a.b2-a.ab + b.a2 + b.b2-b.ab)


= a3 + ab2 + a2b-a2b-b3-ab2-a3-ab2 + a2b-a2b-b3 + ab2


= -2b3


Therefore, (a - b) (a2 + b2 + ab) - (a + b) (a2 + b2 - ab) = -2b3
Method 2:
We know that,
(a - b) (a2 + b2 + ab) = a3 - b3 and (a + b) (a2 + b2 - ab) = a3 + b3
Therefore,
(a - b) (a2 + b2 + ab) - (a + b) (a2 + b2 - ab) = a3 - b3 - (a3 + b3 ) = -2b3


Question 125.

Simplify

(b2-49)(b + 7) + 343


Answer:

The given expression is

(b2-49)(b + 7) + 343


= b2.b + 7b2-49b-49.7 + 343


= b3 + 7b2-49b-343 + 343


= b3 + 7b2-49b


Therefore, (b2-49)(b + 7) + 343 = b3 + 7b2-49b



Question 126.

Simplify

(4.5a + 1.5b)2 + (4.5b + 1.5a)2


Answer:

The given expression is

(4.5a + 1.5b)2 + (4.5b + 1.5a)2


We have,


(4.5a + 1.5b)2 = (4.5a)2 + 2(4.5a)(1.5b) + (1.5b)2


and


(4.5b + 1.5a)2 = (4.5b)2 + 2(4.5b)(1.5a) + (1.5a)2


Therefore,


(4.5a + 1.5b)2 + (4.5b + 1.5a)2


= (4.5a)2 + 2(4.5a)(1.5b) + (1.5b)2 + (4.5b)2 + 2(4.5b)(1.5a) + (1.5a)2


= (4.5)2(a2 + b2) + 2.2(4.5)(1.5)ab + (1.5)2(a2 + b2)


= (a2 + b2)( (4.5)2 + (1.5)2) + 27ab


= 22.5(a2 + b2) + 27ab



Question 127.

Simplify

(pq-qr)2 + 4pq2r


Answer:

The given expression is

(pq-qr)2 + 4pq2r


= (pq)2-2(pq)(qr) + (qr)2 + 4pq2r


= p2q2-pq2r + q2r2 + 4pq2r


= p2q2 + 3pq2r + q2r2


Therefore , (pq-qr)2 + 4pq2r = p2q2 + 3pq2r + q2r2



Question 128.

Simplify

(s2t + tq2)2 – (2stq)2


Answer:

The given expression is

(s2t + tq2)2 – (2stq)2


= (s2t)2 + 2(s2t)(tq2) + 2(s2t)(tq2)-4s2t2q2


= s4t2 + 2s2t2q2 + 2s2t2q2-4s2t2q2


= s4t2


Therefore ,(s2t + tq2)2 – (2stq)2 = s4t2