Page 230 - Maths Skills - 8

228 Maths

Exercise - 6.3

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1. (i) False, perfect square trinomial is 81 x – 72 xy + 16 y (ii) False, correct factorisation is (x – 6) (x + 6) (iii) True (iv) False
2. (i) (a + 3)(a + 1) (ii) (p – 3)(p + 5) (iii) (x – 5)(x + 3) (iv) (n – 2)(n – 5) (v) (t + 6)(t + 4) (vi) (l + 7)(l – 11)
(vii) (a – 8)(a + 9) (viii) (q + 13)(q – 8) (ix) (c – 11)(c + 12) (x) (4x + 1)(3x + 2) (xi) (5n + 2)(n + 3) (xii) (3b + 10)(b + 2)
(xiii) (2g + 3)(3g + 4) (xiv) (m – 4) (3m + 2) (xv) (3y + 1)(y + 5) (xvi) (4n + 2)(3n – 2)
3. (i) (x – a)(x – a) (ii) (x – 13)(x + 2) (iii) (x – 2)(x – 12) (iv) (x – 3)(2x + 1) (v) 2(7x + 3)(2x + 5) (vi) 3(2x + 1)(5x – 7)
(vii) (3q – 5)(3q – 5) (viii) (9x – 7)(5x + 4)

Exercise - 6.4

yz xy
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1. (i) (ii) 5x (iii) –54 2. (i) p – p + 5 (ii) + 4 x (iii) 9x y – 6x + 3 3. (i) x – x + 2
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x 3 2
(ii) x + 4x + 4 (iii) x – x + 2 (iv) a – 1 (v) x + x + 1 (vi) x + x + 2 4. (a + a + 1)(a – 1 ) = (a – 1 )
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Assessment Time
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A. 1. (i) 2. (i) 3. (ii) 4. (iv) 5. (i) 6. (iii) B. 1. 3x + 4x + 6 2. a + b 3. 6x – 3x + 2
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C. 1. F 2. T 3. F 4. F 5. T D. 1. (2x – 3) meter 2. ` 3. 55 units 2
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E. 1. (a) 2. (d) 3. (a) F. 1. (4x + 12x + 9) (2x + 3) = 8x + 36x + 54x + 27 2. k = 12 3. p = 7 4. – 3x + 2
G. (x + 2) (x + 7)
HOTS
1. (x + 2)(x – 5)(x – 5) 2. (x + 5y )(x + 4y )(x + 2y)(x – 2y) 3. 27( y + 22)(y − 2) 4. ab(9a + 5b)(a + 4b)
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Assessment - 2
1. (b) 2. (c) 3. (b) 4. (a) 5. (d) 6. (a) 7. negative 8. 4913 9. 5 10. 3x
11. Factorisation 12. True 13. False 14. True 15. False 16. False 17. 3x – x – 5x + 3 18. 944
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19. (a) 20. (a) 21. 5 22. (p + 3)(p + 2) 23. 21 24. Do yourself 25. Q = –3x + 4, R = 11x – 3
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26. x = 0 27. 7 28. (p + q + 2) (p + q – 2) 29. 9
Chapter - 7: Linear Equations in One Variable
Boot-up
A. 1. (iii) 2. (iii) 3. (iv) 4. (ii) B. 1. 6 2. – 2 3. not exist 4. negative
C. 1. F 2. F 3. T 4. T
Exercise - 7.1
1. (i) x = 6 (ii) x = 11 (iii) x = 1 (iv) x = 3 (v) t = 2 (vi) x = 3 2. (i) x = 23 (ii) a = 3 (iii) b = 1 (iv) x = 2
3 3 2
3. (i) x = – 5 (ii) x = 3 (iii) x = 1 (iv) x = 2 (v) x = 4 (vi) y = 10 (vii) y = 8 (viii) x = 3 (ix) x = 0 (x) x = 3
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(xi) x = −18 (xii) x = −8
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Exercise - 7.2

1. 20, 22, 24 2. 21, 23, 25 3. 30 4. 10 5. 36 6. 24 7. 10, 8
8. 324, 333, 342 9. 252, 259, 266 10. 8 11. 1 part 100, 2 part 50, 3 part 150 12. A = 15 years, B = 5 years, C = 20 years
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nd
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13. 35 years, 25 years 14. 90°, 30°, 60° 15. length = 80 m, breadth = 40 m and length = 72 m, breadth = 48 m 16. length = 35 m, breadth = 10 m