Page 310 - ICSE Math 7

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–1
3. 10.4 km h 4. 400 km 5. 5 h 6. 364 km; 5.6 h Exercise 12.4
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7. 315 m 8. 402.5 km 1. (a) –4 (b) –6 (c) –2 (d) 1
2. (a) 2 (b) 1 (c) 9 (d) 4
Think Smart 3. (a) 4 (b) –4 (c) 8 (d) 4
1. 75 km 2. 10 m s –1 4. (a) 2x + 8; 4 (b) –x + 15; 17 (c) 16x + 2; –30

Chapter 12 5. (a) –6 (b) 2 6. 8
Mental Maths
Exercise 12.1
1. (a) 18x – 25 = 191 (b) 2y + 56 = 84 1. (a) (iii) (b) (ii) (c) (iv) (d) (i) (e) (ii)
(c) –6q = 114 (d) –3y + 18 = 26 2. (a) False (b) True (c) True (d) False (e) False
2. (a) Binomial (b) Monomial (c) Monomial (f) True (g) True (h) True 2
(d) Binomial (e) Trinomial (f) Binomial 3. (a) –3ab (b) 0 (c) –15pq (d) 13x y
b
12a
2 3
2
(g) Trinomial (h) Monomial (e) l m n (f) b – (g) 3x – 2 (h) subtracted
a
3. (b), (c) and (e) Practice Time
3 7 2
4. (a) 16 (b) –13y (c) x yz (d) –yz 1. (a) Binomial (b) Monomial (c) Binomial
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5. (b) 2 (d) 6 (e) 3 (d) Trinomial 2
2. (a) 4x (b) 3x (c) –5x z (d) –3x
2
6. (a) 5 (b) –9 (c) 4; –1; 3 (d) 4 3 2 2 2 3
11 3. x – 7x + 3x + 4 4. –3x y + xy + y + 5
3
4
Exercise 12.2 5. mn – 3mn + 2mn + 6 6. –10
14 2
2
2
1. (a) 7mn (b) xyz – 2xy (c) 9a – 3b (d) 7ab 7. 3a + ab + 2; 35 8. a = 3
15 9. (x – 5) = 2(x – 10), where x is Karishma’s age
2
2
(e) 5p – pq (f) –5x – 15y 2 10. 10 trees; 16 trees 11. (10x + 2y) units
2
2. (a) –13x (b) –7x + 5 (c) 3 – 12abc (d) 9a b – 6ab 2 12. (3p + 1) units; (12p) units
2
2
(e) 9p – 12p q + 3 (f) –2b 2 1
2
2
4
2
3. (a) 6a – b – a (b) 11xy + 3y – x 2 13. ` 3y – 2 + y
2
2
2
2
(c) 2q + 3pq + p – 5 (d) 5lm – 4ml + mn + 30 14. (a) 21a – 4b (b) –3mn + 3lm + 3ln
2
2
2
4. (a) –2xy + 6y (b) –4lmn + 9mn (c) 6a + 5b – 20ab (c) 2(x – y ) (d) 6a + 2a + 5
2
2
2
(d) –2pq – 4qr
2
2
2
2
5. –9ab + 3bc – 3a + b 6. 5xy – 2y – 2x – 2 Think Smart 2
2
2
7. –32pq – 15pq – 5p + 15 1. (5x – 4) m; 42 m 2. 6
2 2
2
3
8. 2ab + 4a b – 12b – 2ab 2 Chapter 13
9. 9x – 6y + 6z 10. (14x + 3y) cm
Exercise 13.1
Exercise 12.3 1. (i) No (ii) Yes (iii) No (iv) Yes
2
3
2
2
1. (a) 27a (b) –12x (c) –90a b (d) 4l m (e) 32x 4 2. (a) Yes (b) Yes (c) No
2
2
3 3
(f) 28a xy (g) 25a b 3. (a) 9a + 6 = 24, where Simran’s age is y
b
3 2
2 3
3
2
4
2. (a) 6x + 15x y (b) –20a b – 12a b + 4a b (b) = 5 (c) 5y – 12 = 40
7
4
2
5 2
(c) –40a bx (d) –80p q (e) 42x –85xy + 42y 2 (d) 3y + 5 = 41, where Simran’s are is y
2
2
2
2
2
2
(f) x y + x z + y z + y x + yz + xz + 3xyz (e) x + 2x + 2x = 180° where vertex angle is x
2
2
2 2
4
3. (a) a – b (b) a – 2a b + b 4 (f) n + (n + 2) = 44, where n is an odd number
6
4 2
2 4
(c) a – a b – a b + b 6 4. (a) 7 added to x gives 9
–3 –5q 2 (b) Three times p divided by sum of p and 5 gives 16
4. (a) (b) (c) 5pq (d) –5xy 6
4 x (c) A number exceeding 4 times p by 2 equals 20
6 3
9p q 3q 4 2b 2
(e) – (f) b + – 4b 3 (d) Twice of x diminished by 5 gives 20
r r 2 a
5. (a) Quotient = 4x + 2y; Remainder = 0 Exercise 13.2
2
(b) Quotient = 3a – 35a ; Remainder = –25a 1. (a) p = 9 (b) x = 0 (c) p = 17 (d) m = –2
6 6 2. (a) Subtract 4 from both sides ⇒ y = 2
2
(c) Quotient = (3l + 3l – 3); Remainder = 0 (b) subtract 5 from both sides ⇒ x = 3
(d) Quotient = p; Remainder = 6 (c) Add 6 on both sides ⇒ x = 19
6. (l + b) units; (12l – 4b) units (d) Multiply both sides by 2 ⇒ x = 16
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