Page 290 - ICSE Math 6

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a b 4. (a) –x + 5 (b) 13a + 2b (c) 45 – 40x
3. 5 4 2 (i) x = –1 (j) x = 1 (k) y = 1 (l) z = 1 1
9 6 8 9
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(d) –5x + 8y + 2 (m) z = 8 (n) x = –2
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5. (a) 11 (b) 19 (c) –9 4. (a) z = 0 (b) x = 0 (c) z = 27 (d) z = –7
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6. (a) –3 (b) 13 (c) 6 (d) 7 (e) 6 (f) 22 (e) y = 34 (f) x = –3 (g) x = 1 (h) x = 13
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Mental Maths (i) y = 11 2
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1. (a) 5ab (b) –pq (c) 5a b (d) 8xy (e) 12abxy Exercise 13.2
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(f) 12x y (g) –a – x (h) –2 – xy (i) 3 – 2x 2 1. 19 2. 17; 18; 19 3. 36 4. 11 5. 54
2. (a) False (b) True (c) False (d) True 6. 33 7. 21; 22 8. 14 years
9. Daughter’s age = 17 years; Women’s age = 46 years
Practice Time 10. Boys = 15; Girls = 20
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a
1. (a) 10a (b) 21x (c) –ab + 2xy (d) –2 4
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(e) p q + q (f) –2xy –10yz Mental Maths
7 7 1. (a), (b), (c) and (e)
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2. (a) 2xy (b) 5mn – 7m (c) –3pq (d) –13 xy 2. (a) 9 (b) y (c) 3y (d) y
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(e) 54 2 4 3 3. (a)–(iii); (b)–(v); (c)–(i); (d)–(ii); (e)–(iv)
x y (f) mn – 3mn
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3. (a) 20ab – 4b + 5 (b) –8x (c) 6p – 2p + 6q Practice Time 1
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(d) 6ab + 5bc – ca – 9 (e) 8x – 4y – 3z 2 1. (a) 3x = 27 (b) 2y – 13 = 11 (c) 2x + 5 = x
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(f) –10a + 19b – 15 (d) x + (x + 1) + (x + 2) = 33 or 3x + 3 = 33
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4. (a) –24x (b) 15a b (c) –15x y z 2. (a) 4 subtracted from thrice of z gives 6.
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x y – mn 6. 2xy –
5. 33 2 17 x + y (b) The sum of 4 times of y and 5 is two-fifths of y.
13 4 2 (c) One-third of x when added to 9 gives 7.
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7. 24a b (d) 5 divided by y is 29.
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8. (a) 9a (b) 2y – 11 (c) 2 – 6a + 4b (d) 11 + 44p (e) 7 times x plus 2 is 0.
(e) –12x – 2y (f) 3 – 10ab + 9b (f) 8 more than x is 6.
9. (a) 27 (b) 8 (c) 15 (d) 29 (e) 16 (f) 38 3. (a) x = 2 (b) y = 7 (c) z = –4 (d) a = –4
10. (i) 350g + 250s (ii) ` 65,500 11. ` 3,360 3
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(e) x = 2 (f) z = 0 (g) x = (h) a = 2
Think Smart 9 2 11
1. (a) and (c) 2. (c) 3. binomial 4. 13 4. (a) a = 5 (b) a = (c) x = 8 (d) x = 13
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Chapter 13 (e) z = 2 (f) x = 7
5. 10 6. 11 7. 45
Exercise 13.1
1. (a) x + 21 = 30 (b) 2x – 9 = 11 (c) 10 – x = 3 8. Boy’s age = 18 years; Brother’s age = 24 years
18 1 2 9. Son’s age = 15 years; Man’s age = 43 years
(d) = 6 (e) x + x = 135
x 4 7 10. 15 litres; 29 litres 11. 50 12. 25
(f) x + (x + 1) = 21 or 2x + 1 = 21
Think Smart
2. (a) x subtracted from 15 gives 6. 1. 30 coins
(b) 4 subtracted from four times of x equals 76. 2. Rectangle A: length = 10 units, breadth = 5 units;
(c) a when increased by 3 is equal to 5. Rectangle B: length = 6 units, breadth = 4 units
(d) Thrice of a when increased by 9 gives 15. 3. 7; 14; 28; 56; 112
(e) a subtracted from 7 is equal to 2.
(f) 10 divided by x equals 1. Exercise 14.1 Chapter 14
(g) y when increased by 5 is equal to 10. 1. (a) False (b) False (c) True (d) True
(h) Thrice of z when decreased by 10 is equal to 2.
1 (e) True (f) False
3. (a) a = 1 (b) x = 18 (c) x = 10 (d) y = 0
2 2. (a) 1 (b) 2 (c) 0
(e) x = –60 (f) z = 40 (g) y = –4 (h) x = 12 3. (a) 10 (b) 6 (c) 9

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