Page 229 - Maths Skills - 8

Answers 227

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2. (i) – 6x – 5x y – 9x + 6y + 6y ; 88 (ii) x – y ; 117 (iii) 8x + 27y ; – 3439 (iv) x + y ; – 61
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(v) 4x + 23 x y + 61 xy + 2 y ; 781 (vi) x – x y + x y – x y + xy – y ; – 11571
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6 30 5 3
3. (i) 36x + 15x – 6x (ii) – 2x – 6x + 13x – 21x + 70 (iii) 30x – 23x – 197x + 120 (iv) x – x – 9x + 9
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4. (i) 15x + 8x – 6x – 4 (ii) x y + x yz + xy + y z + xyz + yz 3 (iii) x + y 3
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(iv) 15x + 10x y + 3xy +2y (v) x – x y + x y + x y – xy + y 5 (vi) 1 x − 3 x y − xy + 3y + 2 x − 2y
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5. (i) – 4y + 21y + 8 (ii) – 3x + 2xy – y (iii) 10x + 3xy – y – y (iv) – 3a – 7a + 25a – 18
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Exercise - 5.4
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1. (i) 25x – 81 (ii) x – y 4 (iii) x − 1 2. (i) 25x – 30xy + 9y 2 (ii) y – 6y + 9 (iii) 9 x − 5 xy + 25 y 2
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x 2 16 4 36
3. (i) x + 6x + 9 (ii) 4a + 12ab + 9b 2 (iii) 4 x + 2 20 x + 25 4. (i) 3048 (ii) 34.68 (iii) 98
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(iv) 3.46 5. 7 6. (i) 10404 (ii) 96721 (iii) 5184 (iv) 7921 (v) 13924
(vi) 978121 (vii) 91 (viii) 4891 (ix) 80.91 (x) 143.75 (xi) 9975 (xii) 22491
Assessment Time
A. 1. (ii) 2. (i) 3. (iv) 4. (i) 5. (iv) B. 1. monomial 2. binomial 3. (a + b) 2
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4. a – b C. 1. F 2. F 3. T 4. F D. 1. V = 6x (x – 2x + 4) –2xy (x –2x + 4) m 3
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3x − y (3x y )(5x ) 3 −7 −7
2. 3. ` E. 1. (a) 2. (a) F. 1. 2x + 7x + 4 2. x y z ;
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8x 8 6 27648
3. 138 4. 62 ; 3842 5. 6
HOTS
1. (i) x + 4y + 9z – 4xy – 12yz + 6zx (ii) 4x + 25y + 49z – 20xy – 70yz + 28zx (iii) 16p + 9q + 4r – 24pq + 12qr – 16pr
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1 9 3 15 1
(iv) 25a + b + c − 5ab + bc − ca (v) 4x + y + 64z – 4xy – 16yz + 32zx (vi) l + m + 36 + lm + 6m + 12l
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4 16 4 2 4
2. (i) 2a + 2b + 2c + 4bc (ii) – 4bc + 4ca (iii) 0 (iv) 8lm – 12nl
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Chapter - 6: Factorisation
Boot-up
A. 1. (iii) 2. (iv) 3. (i) 4. (iii) B. 1. 18 2. 80 3. 73 4. 2 5. 3
C. 1. True 2. True 3. True 4. True
Exercise - 6.1
1. (i) 6(a + 4) (ii) 4b (2b – 1) (iii) 4(x +2x + 3) (iv) 3a(5x – 2y) (v) 5xy (3y – 5x + 2)
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(vi) 3abc (abc + 9a b c – 27) (vii) 3x (3x – 5x – 6) (viii) 18y (2 – y + 3y )
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2. (i) (2m – 3) (4m + 5) (ii) (m – 4)(m + 3) (iii) (t – 2) (2t + 1) (iv) (2y – 5)(3y + 2) (v) (b – 1)(ab – c )
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(vi) (a + 1)(a – 3) (vii) z(4x + 3y) (viii) (7x – 2)(3x b – 3b)
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3. (i) (3u + 2k) (4v + k) (ii) (6x – 5a) (y + 3x) (iii) (32x + 4m) (6y + 1) (iv) 7m (m + 8n) (2m + b)
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(v) (3y + 7) (28x – 12) (vi) (b + 1) (ab – 1)
Exercise - 6.2
1. (2x – 5)(2x + 5) 2. (ax – 5)(ax + 5) 3. (1 + 6y )(1 – 6y ) 4. 2(x – 3)(x + 3)
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5. (2x + 6y)(2x + 6y) 6. (2x – 1 4 )(2x + 1 4 ) 7. (m + 11)(m + 11) 8. –2(y – 3)(y – 3)
9. a(m – 7)(m – 7) 10. (xy – 8)(xy + 8) 11. –b(x + 6) (x + 6) 12. (4x – 10)(4x + 10)
13. (5a – cd) (5a + cd) 14. 5(a + 1)(a + 1) 15. (t + 9)(t + 9) 16. (x + 10)(x + 10)
17. (m + 8)(m + 8) 18. (2a – b + 3)(2a + b – 3) 19. (16 – x)(6 + x) 20. (3p – 4q – 9a)(3p – 4q + 9a)