InterviewSolution
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| 51. |
Factorise: 16p3 - 4p |
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Answer» 16p3 -4p can be written as 4p (4p2 – 1) By using the formula a2 – b2 = (a+b) (a-b) Now solving for the above equation 4p (4p2 – 1) = 4p ((2p)2 – (1)2) = 4p (2p+1) (2p-1) |
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| 52. |
Class 8 Maths MCQ Questions of Factorisation with Answers? |
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Answer» Students are advised to solve the MCQ Questions for Class 8 Maths to know different concepts. Use MCQ Questions for Class 8 Maths with Answers during preparation and score maximum marks in the exam. These MCQ Questions are designed by subject experts, according to the latest syllabus and NCERT guidelines. Class 8 Maths MCQ Questions of Factorisation with answers are available online for students. The chapter-wise Multiple Choice Questions are provided at Sarthaks eConnect to make all students learn each concept and help them to score best marks in exams. Also, learn important MCQ Questions of Factorisation Class 8 with answers provided with detailed solutions. Practice MCQ Question for Class 8 Maths chapter-wise 1. The common factor of x2y2 and x3y3 is (a) x2y2 2. The common factor of x3y2 and x4y is (a) x43y2 3. The common factor of a2m4 and a4m2 is (a) a4m4 4. The common factor of 2x, 3x3, 4 is (a) 1 5. The common factor of 10ab, 30bc, 50ca is (a) 10 6. The common factor of 14a2b and 35a4b2 is (a) a4b2 7. The common factor of 72x3y4z4, 120z2d4x4 and 96y3z4d4 is (a) 96z3 8. The factorisation of 12a2b + 15ab2 is (a) 3ab (4a + 5b) 9. The factorisation of x2yz + xy2z + xyz2 is (a) xyz(x + y + z) 10. The factorisation of a (x + y + z) + b(x + y + z) + c(x + y + z) is (a) (a + b + c)(x + y + z) 11. The factorisation of 6xy – 4y + 6 – 9x is (a) (3x – 2)(2y – 3) 12. The factorisation of x2 + xy + 2x + 2y is (a) (x + 2)(x + y) 13. The factorisation of ab – a – b + 1 is (a) (a – 1)(b – 1) 14. The factorisation of x2 + x + xy + y + zx + z is (a) (x + y + z)(x + 1) 15. The factorisation of x2 + 8x + 16 is (a) (x + 2)2 16. The factorisation of 36x2y2 – 1 is (a) (6xy – 1)(6xy + 1) 17. The value of (0.68)2 – (0.32)2 is (a) -1 18. The factorisation of 3x2+ 10x + 8 is (a) (3x + 4)(x + 2) 19. The factorisation of 6x2 – 5x – 6 is (a) (2x – 3)(3x + 2) 20. The quotient of 28x² + 14x is (a) 2 21. On factorising 14pq + 35pqr, we get: (a) pq(14 + 35r) 22. Divide as directed: 52pqr (p + q) (q + r) (r + p) ÷104pq (q + r) (r + p) (a) r(p+q) 23. The factors of 3m2 + 9m + 6 are: (a) (m + 1) (m + 2) 24. The factors of m2 – 256 are: (a) (m + 4)2 25. The factors of 49p2 – 36 are: (a) (7p + 6)2 Answer: 1. Answer: (a) x2y2 Explanation: x2y2 = x × x × y × y x3y3 = x × x × x × y × y × y 2. Answer: (d) x3y Explanation: x3y2 = x × x × x × y × y x4y = x × x × x × x × y 3. Answer: (b) a2m2 Explanation: a2m4 = a × a × m × m × m × m a4m2 = a × a × a × a × m × m 4. Answer: (a) 1 Explanation: 2x = 2 × x 3x3 = 3 × x × x × x 4 = 2 × 2 Hence the common factor is 1 5. Answer: (a) 10 Explanation: 10ab = 2 × 5 × a × b 30bc = 2 × 3 × 5 × b × c 50ca = 2 × 5 × 5 × c × a Hence common factor is 2 x 5 = 10 6. Answer: (d) 7a2b Explanation: 14a2b = 2 × 7 × a × a × b 35a4b2 = 5 × 7 × a × a × a × a × b × b 7. Answer: (d) 24z2 Explanation: 72x3y4z4 = 2 × 2 × 2 × 3 × 3 × x × x × x × y × y × y × y × z × z × z × z. 120z2d4x4 = 2 × 2 × 2 × 3 × 5 × z × z × d × d × d × d × x × x × x × x 96y3z4d4 = 2 × 2 × 2 × 2 × 2 × 3 × y × y × z × z × z × z × d × d × d × d Hence common factor is 2 x 2 x 2 x 3 = 24z2 8. Answer: (a) 3ab (4a + 5b) Explanation: 12a2b + 15ab2 = 3ab(4a + 5b) 9. Answer: (a) xyz(x + y + z) Explanation: x2yz + xy2z + xyz2 = xyz (x + y + z) 10. Answer: (a) (a + b + c)(x + y + z) Explanation: a(x + y + z) + b(x + y + z) + c(x + y + z) = (x + y + z) (a + b + c) 11. Answer: (a) (a + b + c)(x + y + z) Explanation: 6xy – 4y + 6 – 9x = 2y(3x – 2) – 3(- 2 + 3x) = (3x – 2)(2y – 3) 12. Answer: (a) (x + 2)(x + y) Explanation: x2 + xy + 2x + 2y = x(x + y) + 2(x + y) = (x + 2) (x + y). 13. Answer: (a) (a - 1)(b -1) Explanation: ab – a – b + 1 = a(b – 1) – 1(b – 1) = (a – 1)(b – 1) 14. Answer: (a) (x + y + z)(x + 1) Explanation: x2 + x + xy + y + zx + z = x(x + 1) + y(x + 1) + z(x + 1) = (x + 1)(x + y + z) 15. Answer: (b) (x + 4)2 Explanation: x2 + 8x + 16 = (x)2 + 2 (x)(4) + (4)2 ((a + b)2 = a2 + 2ab + b2)) = (x + 4)2. 16. Answer: (a) (6xy – 1)(6xy + 1) Explanation: 36x2y2 – 1 = (6xy)2 – (1)2 ((a2 - b2) = (a+b)(a-b)) = (6xy – 1)(6xy + 1) 17. Answer: (d) 0.36 Explanation: (0.68 + 0.32) (0.68 – 0.32) = 0.36. 18. Answer: (a) (3x + 4)(x + 2) Explanation: 3x2 + 10x + 8 = 3x2 + 6x + 4x + 8 = 3x(x + 2) + 4(x + 2) = (x + 2)(3x + 4) 19. Answer: (a) (2x – 3)(3x + 2) Explanation: 6x2 – 5x – 6 = 6x2 – 9x + 4x – 6 = 3x(2x – 3) + 2(2x – 3) = (2x – 3)(3x + 2) 20. Answer: (b) 2x Explanation: \(\frac{28x^21}{14x}\) \(=\frac{2\times2\times7\times x\times x}{2\times7\times x}\) = 2x 21. Answer: (d) 7pq(2 + 5r) Explanation: 14pq + 35pqr = 2.7.p.q + 5.7.p.q.r = 7pq(2 + 5r) 22. Answer: (b) 1/2 r(p+q) Explanation: 52pqr(p+q)(q+r)(r+p)÷104pq(q+r)(r+p) \(=\frac{52\times p\times q\times r\times (p+q)\times(q+r)\times(r+p)}{52\times2\times p\times q\times(q+r)\times(r+p)}\) = \(\frac{1}{2}r(p+q)\) 23. Answer: (b) (b) 3[(m + 1) (m + 2)] Explanation: 3m2 + 9m + 6 = 3(m2 + 3m + 2) = 3 [m2 + m + 2m + 2] = 3 [m(m + 1)+ 2( m + 1)] = 3 [(m + 1) (m + 2)] 24. Answer: (d) None of the above Explanation: m4 = (m2)2 and 256 = (16)2 m4 – 256 = (m2)2 – (16)2 = (m2 – 16) (m2 + 16) m2 – 16 = m2 – 42 = (m – 4) (m + 4) m4 – 256 = (m – 4) (m + 4) (m2 + 16) 25. Answer: (d) None of the above Explanation: 49p2 – 36 = (7p)2 – ( 6 )2 = (7p – 6 ) ( 7p + 6) ((a2 - b2) = (a+b)(a-b)) |
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| 53. |
Factorise : x2 + 4x + 3 |
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Answer» x2 + 4x + 3 = x2 + 3x + x + 3 = x(x+3) + 1(x + 3) = (x+3) (x+1) |
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| 54. |
\((\frac{3001}{6})^2 - (\frac{2999}{6})^2\) = .....................(3001/6)2 - (2999/6)2A) 333 \(\frac{1}{3}\)B) 343 \(\frac{1}{2}\)C) 243 \(\frac{1}{2}\)D) 712 \(\frac{1}{2}\) |
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Answer» Correct option is A) 333 \(\frac{1}{3}\) Correct option is (A) \(333\frac13\) \((\frac{3001}6)^2-(\frac{2999}6)^2\) \(=\frac{3001^2-2999^2}{6^2}\) \(=\frac{(3001+2999)(3001-2999)}{36}\) \(=\frac{6000\times2}{36}=\frac{1000}3\) \(=\frac{333\times3+1}3\) \(=333+\frac13\) = \(333\frac13\) |
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| 55. |
(b + 1) (3a + 2) = ………….. A) 3ab – 2b + 1 B) 3ab – 2 C) 3ab + 2 D) 3ab + 3a + 2b + 2 |
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Answer» D) 3ab + 3a + 2b + 2 Correct option is (D) 3ab + 3a + 2b + 2 (b + 1) (3a + 2) = 3ab + 3a + 2b + 2 |
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| 56. |
(x + 8)2 = x + □ + 64 A) 6x B) 4xC) 16x D) x/4 |
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Answer» Correct option is C) 16x Correct option is (C) 16x \((x+8)^2=x^2+2\times x\times8+8^2\) \(=x^2+16x+64\) \(\therefore\Box=16x\) |
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| 57. |
Factorise: x2 + x – 132 |
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Answer» First find the two numbers whose sum= 1 and product= -132 Clearly, the numbers are 12 and 11 ∴ we get, x2 + x – 132 = x2 + 12x – 11x – 132 = x(x+12) – 11(x+12) = (x+12) (x-11) |
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| 58. |
Factorise: ax – 56 + ab – 5x. |
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Answer» ax-5b+ab-5x ax+ab-5b-5x a (x+b)-5 (b+x) (x+b)(a-5) |
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| 59. |
Factorise: x2 + 5x – 104 |
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Answer» First find the two numbers whose sum= 5 and product= -104 Clearly, the numbers are 13 and 8 ∴ we get, x2 + 5x – 104 = x2 + 13x – 8x – 104 = x(x+13) – 8(x+13) = (x+13) (x-8) |
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| 60. |
Factorise: x2 – 23x + 42 |
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Answer» First find the two numbers whose sum= -23 and product=42 Clearly, the numbers are 21 and 2 ∴ we get, x2 – 23x + 42 = x2 – 21x – 2x + 42 = x(x-21) – 2(x-21) = (x-21) (x-2) |
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| 61. |
Factorise completely : a2 + 2ab + b2 – c2 |
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Answer» a2 + 2ab + b2 – c2 = (a2 + 2ab + b2)- c2 = (a + b)2 - (c)2 = (a + b + c) ( a + b - c) |
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| 62. |
Factorise completely : 625 – x4 |
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Answer» 625 – x4 = (25)2 - (x2)2 = (25 + x2) (25 - x2) = (25 + x2) [(5)2 - (x)2] = (25 + x2) (5 + x) (5 + x) |
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| 63. |
Factorise completely : x2 – y2 – 2x + 2y |
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Answer» x2 – y2 – 2x + 2y = (x2 – y2) - 2(x - y) = (x + y) (x - y) - 2(x - y) = (x - y) (x + y)- 2) |
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| 64. |
Factorise completely : 8x2y – 18y3 |
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Answer» 8x2y – 18y3 = 2y(4x2 - 9y2) = 2y[(2x2 - (3y)2] = 2y(2x + 3y) (2x - 3y) |
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| 65. |
Factorise: x2 + 8x + 16 |
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Answer» We solve by using the formula (a+b) 2 = a2 + b2 + 2ab We get, x2 + (4)2 + 2 (x) (4) = (x+4)2 |
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| 66. |
0 ÷ 36 (x – 4) = ……………… A) 0 B) 6 C) 3 D) 10 |
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Answer» Correct option is A) 0 Correct option is (A) 0 0 \(\div\) 36 (x – 4) \(=\frac0{36(x-4)}\) = 0 |
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| 67. |
(x + 3) (x + 6) = ……………. A) x2 – 3x B) x2 + 9x + 18 C) x – 3x2 D) None |
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Answer» B) x2 + 9x + 18 Correct option is (B) x2 + 9x + 18 (x + 3) (x + 6) \(=x^2+6x+3x+18\) = \(x^2+9x+18\) |
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| 68. |
11 xy2 z3 ÷ 55 xyz = ……………..A) \(\frac{x}{y^2}\)B) \(\frac{5z}{x}\)C) \(\frac{y}{z}\)D) \(\frac{yz^2}{5}\) |
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Answer» Correct option is D) \(\frac{yz^2}{5}\) Correct option is (D) \(\frac{yz^2}5\) \(11\,xy^2z^3\div55\,xyz\) \(=\frac{11\,xy^2z^3}{55\,xyz}\) = \(\frac{yz^2}5\) |
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| 69. |
Factorise : a3b - a2b2 - b3 |
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Answer» a3b - a2b2 - b3 = b(a3 - a2b - b2) |
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| 70. |
Factorise : 6x2y + 9xy2 + 4y3 |
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Answer» 6x2y + 9xy2 + 4y3 = y(6x2 + 9xy + 4y2) |
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| 71. |
Factorize : `x^2+9x+18` |
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Answer» `x^2+9x+18` `x^2+6x+3x+18` `x(x+6)+3(x+6)` `(x+6)(x+3)`. |
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| 72. |
`x^2-3x+3y-y^2` |
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Answer» `x^2 - 3x + 3y - y^2` `x^2 - y^2 -3x+3y` `(x-y)(x+y)-3(x-y)=0` `(x-y)(x+y-3)=0` Answer |
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| 73. |
simplify `(y^2 + 7y+10)/(y+5)` |
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Answer» `y^2+7y+10 = y^2+5y+2y+10=y(y+5)+2(y+5) = (y+2)(y+5)` `:. (y^2+7y+10)/(y+5) = ((y+2)(y+5))/(y+5) = (y+2)` |
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| 74. |
`(5a^3-4a^2+3a+18)/(a^2-2a+3)` |
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Answer» `(5a^3-4a^2+3a+18)/(a^2-2a+3)` `=5a+6` |
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| 75. |
Factorise:x2 – x – 72 |
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Answer» x2 – 9x + 8x – 72 x(x – 9) + 8(x – 9) (x – 9)(x + 8) |
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| 76. |
Factorise :4x2 + 4x + 1 |
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Answer» 4x2 + 4x + 1 Identity a2 +2ab + b2 =(a + b)2 = (2x)2 + (2)(x)(1) +12 = (2x +1)2 |
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| 77. |
Factorise :x2 + 14x + 49 |
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Answer» x2 + 14x + 49 Identity a2 + 2ab + b2 = (a + b)2 = x2 + 2 × x × 7 + 72 = (x + 7)2 |
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| 78. |
Find and correct the errors in the statement: 3x + 2x = 5x2 |
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Answer» L.H.S. = 3x + 2x = 5x ≠ R.H.S The correct statement is 3x + 2x = 5x |
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| 79. |
Find and correct the errors in the statement: (a + 4) (a + 2) = a2 + 8 |
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Answer» L.H.S. = (a + 4) (a + 2) = (a)2 + (4 + 2) (a) + 4 × 2 = a2 + 6a + 8 ≠ R.H.S The correct statement is (a + 4) (a + 2) = a2 + 6a + 8 |
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| 80. |
Find and correct the errors in the following mathematical statement: (z + 5)2 = z2 + 25 |
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Answer» (2a + 3b) ( a – b) = 2a2 – 3b2 |
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| 81. |
Find and correct the errors in the statement: (2a + 3b) (a − b) = 2a2 − 3b2 |
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Answer» L.H.S. = (2a + 3b) (a − b) = 2a × a + 3b × a − 2a × b − 3b × b = 2a2 + 3ab − 2ab − 3b2 = 2a2 + ab − 3b2 ≠ R.H.S. The correct statement is (2a + 3b) (a − b) = 2a2 + ab − 3b2 |
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| 82. |
Factorise : 5 + 7x - 6x2 |
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Answer» 5 + 7x - 6x2 = 5 + 10x - 3x(1 + 2x) = 5(1 + 2x) -3x(1 + 2x) = (1 + 2x) (5 - 3x) |
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| 83. |
Find and correct the errors in the following mathematical statement. Substituting x = −3 in(a) x2 + 5x + 4 gives (−3)2 + 5 (−3) + 4 = 9 + 2 + 4 = 15(b) x2 − 5x + 4 gives (−3)2 − 5 (−3) + 4 = 9 − 15 + 4 = −2(c) x2 + 5x gives (−3)2 + 5 (−3) = −9 − 15 = −24 |
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Answer» (a) For x = −3, x2 + 5x + 4 = (−3)2 + 5 (−3) + 4 = 9 − 15 + 4 = 13 − 15 = −2 (b) For x = −3, x2 − 5x + 4 = (−3)2 − 5 (−3) + 4 = 9 + 15 + 4 = 28 (c) For x = −3, x2 + 5x = (−3)2 + 5(−3) = 9 − 15 = −6 |
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| 84. |
Factorise : 2a2 - 7b - 17ab + 26b2 |
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Answer» 2a2 - 7b - 17ab + 26b2 = 2a2 - 13ab - 4ab + 26b2 = a(2a - 13b) - 2b (2a - 13b) |
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| 85. |
t (u + at) = ………….. A) ut + at2 B) t + at2 C) t – at2 D) ut – t2 |
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Answer» Correct option is A) ut + at2 Correct option is (A) ut + at2 t (u + at) = \(ut+at^2\) |
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| 86. |
(49x – 63) ÷ 7 = ……………. A) 7x + 1 B) 7x – 9C) x + 3 D) x – 79 |
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Answer» Correct option is B) 7x – 9 Correct option is (B) 7x – 9 (49x – 63) \(\div\) 7 \(=\frac{49x-63}7=\frac{7(7x-9)}7\) = 7x – 9 |
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| 87. |
Find and correct the errors in the statement: (y − 3)2 = y2 − 9 |
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Answer» L.H.S = (y − 3)2 = (y)2 − 2(y)(3) + (3)2 [(a − b)2 = a2 − 2ab + b2] = y2 − 6y + 9 ≠ R.H.S The correct statement is (y − 3)2 = y2 − 6y + 9 |
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| 88. |
Factorise : 6 + 7b - 3b2 |
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Answer» 6 + 7b - 3b2 = 6 + 9b - 2b - 3b2 = 3(2 + 3b) -b(2 + 3b) = (2 + 3b) (3 - b) |
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| 89. |
If x2 + \(\frac{1}{x^2}\) = 62 then x + \(\frac{1}{x}\) = ……….. (x + \(\frac{1}{x}\)> 0) A) 3 B) 8 C) 4 D) 6 |
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Answer» Correct option is B) 8 Correct option is (B) 8 \(x^2+\frac1{x^2}\) = 62 \(\Rightarrow\) \(x^2+\frac1{x^2}+2=62+2\) \(\Rightarrow\) \((x+\frac1x)^2=64=8^2\) \(\Rightarrow\) \(x+\frac1x\) = 8 \((\because\) \(x+\frac1x\) > 0) |
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| 90. |
x – y = …………. A) x√y – 1 B) (√x – √y)(√x + √y) C) (x – √y)(x – √y) D) (√x – y)2 |
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Answer» B) (√x – √y)(√x + √y) Correct option is (B) (√x – √y)(√x + √y) x – y \(=(\sqrt x)^2-(\sqrt y)^2\) = \((\sqrt x-\sqrt y)(\sqrt x+\sqrt y)\) |
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| 91. |
If we divide x2a – 1 by xa – 1 we get …………….. A) x – 1 B) xa – 1C) x + a D) xa + 1 |
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Answer» Correct option is D) xa + 1 Correct option is (D) xa + 1 \(\frac{x^{2a}–1}{x^a–1}=\frac{(x^a)^2–1^2}{x^a–1}=\frac{(x^a-1)(x^a+1)}{x^a–1}\) = \(x^a+1\) |
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| 92. |
a2 – b4 = ………….. A) (a – b) (a – b2) B) (a + b) (a + 1) C) (a – b) (a2 – 1) D) None |
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Answer» Correct option is D) None Correct option is (D) None \(a^2-b^4=a^2-(b^2)^2\) \(=(a-b^2)(a+b ^2)\) |
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| 93. |
(x + 2) (x2 + 5) = ……………..A) x3 + 2x2 + 5x + 10 B) x3 – x2 – 5x + 1 C) x3 – 7x2 + 3 D) x3 – 3x + 7 |
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Answer» A) x3 + 2x2 + 5x + 10 Correct option is (A) x3 + 2x2 + 5x + 10 \((x+2)(x^2+5)\) = \(x^3+2x^2+5x+10\) |
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| 94. |
Factorise : 4 + y - 14y2 |
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Answer» 4 + y - 14y2 = 4 + 8y - 7y - 14y2 = 4(1 + 2y) - 7y(1 + 2y) = (1 + 2y) (4 - 7y) |
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| 95. |
a2 – 2ab + b2 = ……………… A) (a – b)2 B) (a + b)2C) a2 – b2 D) (a + b) (a – b) |
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Answer» Correct option is A) (a – b)2 Correct option is (A) (a – b)2 \(a^2–2ab+b^2\) \(=a^2–ab-ab+b^2\) = a(a-b) - b(a-b) = (a-b) (a-b) = \((a-b)^2\) |
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| 96. |
If x2 – x – 42 = (x + k) (x + 6) then find the value of k. |
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Answer» x2 – x – 42 = (x + k) (x + 6) ⇒ x2 – 7x + 6x – 42 = (x + k) (x + 6) ⇒x (x – 7) + 6 (x – 7) = (x + k) (x + 6) ⇒ (x – 7) (x + 6) = (x + k) (x + 6) On comparison k = – 7 |
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| 97. |
Matching Type Questions.Part 1Part 21. 103 × 107(a) 110212. 22y – 33z(b) 2y3. common factor of 2y, 22xy(c) – 4y4. – 36y3 ÷ 9y2(d) 11 (2y – 3z) |
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Answer» 1. ⇔ (a) 2. ⇔ (d) 3. ⇔ (b) 4. ⇔ (c) |
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| 98. |
Find the factor of 4x2 – a2. |
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Answer» 4x2 – a2 = (2x)2 – a2 = (2x + a) (2x – a) |
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| 99. |
Simplify (x + 2) (x + 3). |
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Answer» (x + 2) (x + 3) = x2 + (2 + 3)x + 2 × 3 = x2 + 5x + 6 |
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| 100. |
If x = 2 and y = – 1 then value of x2 + 4xy + 4y2 is 0. |
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Answer» True If x = 2 and y = – 1 then value of x2 + 4xy + 4y2 is 0. |
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