Page 319 - ICSE Math 8

(g) (a + b )(a + b)(a – b) (h) (x + 2)(x + 2) 10. 20 11. ` 252
2
2
2
2
(i) (x – 1)(x – 1) (j) (12 + x)(2 – x) 12. Aishwarya’s age is 26 years and Karishma’s age is 12 years.
1
(k) 3(3x – 2)(x – 2) (l) (2x + 3y)(2x + 3y – 4) 13. 60 14. 16 kg 15. 18 km h and 80 km 16. 40
–1
2
Exercise 14.5 17. 13 cm and 5 cm
(a) (x – 12)(x – 9) (b) (5 + p)(8 – p) 18. Altitude = 20 cm and base = 12 cm
(c) (4 – x)(x – 5) or (x – 4)(5 – x) (d) (x + 6)(x – 9) 19. 75 km h ; 79 km h –1
–1
(e) (x + 7)(x – 8) (f) (x – 8)(x – 3) Exercise 15.5
(g) (3a – 1)(3a – 1) (h) (2a + 3)(a – 10) 1. (a) {5, 6, 7, 8} (b) {0, 1, 2, 3, 4} (c) {6, 7, 8}
(i) (2x – 1)(x + 4) (j) (5a + 3)(a + 2)
(d) {2, 3, 4, 5, 6, 7, 8} (e) {0, 1} (f) {2, 3, 4, 5, 6, 7, 8}
Mantal Maths (g) {0, 1, 2, 3, 4, 5} (h) {0, 1, 2, 3, 4, 5, 6, 7, 8}
1. (a) (iii) (b) (i) (c) (ii) (d) (iv) (e) (i) 2. (a)
2. (a) False (b) False (c) False (d) True –8 –7 –6 –5 –4 –3 –2 –1 –0 –1 –2
3. (a) literals, product, number (b) 5x y (b) –7 –6 –5 –4 –3 –2 –1 0 1 2 3
3 2
(c) difference (d) a – 4a – 12 (e) 2 – 3x – 9y (c)
2
–3 –2 –1 0 1 2 3
Practice Time ...
1. (a) 9xy (x – 3y) (b) x y (2x – 3xy + 4y) (d) –3 –2 –1 0 1 2 3 4 5 6 7
2 4
2
2
(c) y (p + 2q)(y + 1) (d) (x + 4)(x + 2)(x – 2) (e) ...
2
2
2
0 1 2 3 4 5 6 7
(e) (y + a)(y + b) (f) –4xy (g) (3y – 4) 2 ...
(h) 3xy (5x + 6y)(5x – 6y) (i) (y + y + 1)(y – y + 1) (f)
2
2
2
0 1 2 3 4 5 6 7
(j) (1 + 8x)(3 – x) (k) (x + 4x – y)(x + 5)(x – 1) 3. (a) {9, 10, 11} (b) {2, 3} (c) {0, 1} (d) {18, 19, 20, ...}
2
2. 21 inches and 15 inches (e) {7, 8, 9, ...}
Think Smart 4. (a)
0 1 2 3 4 5
1. (b + 8)(b) = 240; Length = 20 m, Breadth = 12 m (b)
1 2 3 4 5
Chapter 15 (c)
1 2 3 4 5 6 7
Exercise 15.1 (d)
13 35 72 1 13 − 1,470 0 1 2 3 4 5
(a) (b) (c) (d) (e) (f) (e)
5 8 5 2 10 139 0 1 2 3 4 5 6
61 − 60
(g) (h) Mental Maths
7 299
Exercise 15.2 1. (a) (iii) (b) (i) (c) (ii) (d) (iv) (e) (iv)
17 2 2 375 –12 2. (a) True (b) False (c) False (d) True
(a) (b) (c) (d) 3 (e) (f) 3. (a) ax + b ≥ c (b) ≤; ≥; inequality
3 29 3 86 5
170 (c) reversed; multiplied (d) unchanged; subtracted
(g) (h) –2 (i) –4 (j) –10
37 4. (a) (iv) (b) (i) (c) (ii) (d) (iii)
Exercise 15.3 5. (a) x – 4 > 3 (b) x + 3 < 0 (c) –x < –2 (d) –24x > 120
− 1 − 4 54 16
1. (a) 3 (b) 3 (c) –2 (d) 1 (e) (f) (g) Practice Time
18 3 41
− 31 9 5 1. (a) 98 (b) 11 (c) 5 (d) 12 (e) − 11 (f) 2
(h) –4, 4 (i) (j) (k) 36 (l) 91 4 2 9
24 2 2
Exercise 15.4 2. 7, 8, 9 3. 30, 31 4. 16 years, 8 years 5. 45 6. 120
1. 43, 27 2. 48, 12 3. 50, 10 4. 40, 20 5. 71 7. 3,000 notes of ` 50; 4,000 notes of ` 20 and 5,000 notes
of ` 10
13
6. 15, 16 7. 21 8. 62 8. 230 passengers bought tickets of ` 500 each and 250
passengers bought tickets of ` 750 each. Total money
9. 20 coins of ` 1, 60 coins of ` 2, 120 coins of ` 5 paid is ` 3,02,500.

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