Page 228 - Maths Skills - 8

226 Maths

Chapter - 4: Cubes and Cube Roots

Boot-up

A. 1. (iv) 2. (i) 3. (iv) 4. (iv) B. 1. Greater 2. Negative 3. 216 4. 8
C. 1. False 2. False 3. True 4. True

Exercise - 4.1

1. (i) 0.512 (ii) 15.625 (iii) −64 (iv) 125 (v) – 125 (vi) 17 72 (vii) 27 (viii) −2197
343 216 125 64 3375
2. (ii), (iv), (v) and (vii) 3. (i) 343 cm (ii) 91.125 dm (iii) 27000 mm (iv) 3796.416 cm 3
3
3
3
4. (i) 2 (ii) 3 (iii) 2 (iv) 4 5. (i) 3 (ii) 3 (iii) 3 (iv) 6
Exercise - 4.2
1. (i) 45 (ii) 56 (iii) – 72 2. 605, 330 3. (i) 8 (ii) 11 (iii) 12 (iv) 14 4. (i) 6
11
2
(ii) −7 (iii) 4 (iv) 1 5. Do it yourself. 6. 16 m 7. (i) – 21 (ii) – 15 (iii) – 16 (iv) – 18
12 27 3
8. 2, 13 9. – 0.06 10. (i) 0.1 (ii) 0.44 (iii) 1.3 (iv) 1.6
Assessment Time

A. 1. (ii) 2. (ii) 3. (ii) 4. (ii) 5. (iii) B. 1. odd 2. p 3 3. cube root
q 3
3
4. – m 5. m × 3 n C. 1. T 2. T 3. F 4. T 5. T
D. 1. –35 2. false, –9 3. x = –11 4. –0.2 E. 1. (a) 2. (d) 3. (a) F. 1. 7
2. 2 3. 14, 21 and 35 4. 16 and 24

HOTS

1. 2.4 m 2. 170 3. (i) 0.4 (ii) 0.06 (iii) – 4
3
Chapter - 5: Algebraic Expressions and Identities
Boot-up

A. 1. (iv) 2. (iii) 3. (iii) B. 1. variable 2. factors 3. three 4. 0
C. 1. T 2. F 3. T 4. F
Exercise - 5.1

1. (i) 20.35x2 – 23.5x + 17 (ii) 65 x − 2 11 y − 2z (iii) −169 p 2 + 28 q 2 +11r (iv) −19 x (v) −283 ab
2
2
22
9 3 7 5 5 70
2. (i) – 13y2x2 (ii) 86 xy z (iii) −2p 2 + 4p − 2 (iv) 3x2 + 7y2 – 8z2 + 1 (v) – 6a – 14b + 12c – 8
2
5 3
2
3. 4xy + 12x2y2 + 2y2 4. 8y unit 5. –5a + 2a
Exercise - 5.2
12
3 2
3
1. (i) 22x y (ii) 21y (iii) 20x (iv) – 36x yz 2. (i) 30xy z (ii) a b c (iii) – 36a b c (iv) – a b c
3 3 3
2 2 2
4 3
7
2 2 2
3. 3 4. 256 5. – 105a b ; – 1632960 6. (i) 6x + 2xy (ii) – 3x y – 9xy (iii) 12a – 15a 4
2
3
2
2
2
6 5
32 5
3
2 2
3 2 2
(iv) 24a b + 16a b (v) −2 a b c + 1 a b c (vi) 0.7a – 3.5ab
4
2 2 3
3 6
Exercise - 5.3
1. (i) 6x + 2xy – 3xy – y 3 (ii) x – 9xy (iii) x + 4 1 x + 3 1 + 1 (iv) x – ax – a x + a 3
2
2
3
2
2
3
2
2 x 2 2 x 3
(v) 2 x + 3 2 xy + 2 3 x y + 3 y 3 (vi) a b c + a b c +ab c + ab c
3 2
2 2 2
2 3
4
2
7 7 5 5