Page 384 - Start Up Mathematics_8 (Non CCE)

Exercise 7.5 Ê l p ˆ
x
(a) (x – 12)(x – 9) (b) (5 + p)(8 – p) (i) ab(9a + 5b)(a + 4b) (j) Á Ë m x + q ˜ ¯ ( + 1)
(c) (4 – x)(x – 5) or (x – 4)(5 – x) (d) (x + 6)(x – 9)
(e) (x + 1)(x – 6)(x – 3)(x – 2) (f) (x + 7)(x – 8) Exemplar Problems
(g) (x – 8)(x – 3) (h) (3a – 1)(3a – 1) 1. a 2. True 3. True
4
(i) (2x – 3y)(4x – 5y) (j) (3a + 2b)(a + 3b) 4. (a) 7.2 pq (b) x
(k) (2a + 3)(a – 10) Ê 1ˆÊ 1 ˆ
(l) (3x – 4y – 2)(6x – 8y + 1) (m) (2x – 1)(x + 4) 5. (a) (x – 12) (x – 5) (b) x + ˜Á x + + 3 ˜ ¯
Á
¯Ë
Ë
(n) (5a + 3)(a + 2) (o) (2x – y + 4)(6x – 3y + 2) x x
Try It Out! 6. Students to do on their own.
3(2x + 5y) (2x – 5y) Chapter 8
Exercise 7.6 Exercise 8.1
(a) (x + 2)(x + 4) (b) (2x – 3)(2x – 1)
13 (b) 35 (c) 72 (d) 1 (e) 13
(a)
(c) Ê Á Ë x - 5 y + 1 ˆ Ê x - 5 y - 1 ˆ ˜ ¯ (d) Ê Á Ë 1 x + 1 ˆ ˜ ¯ ( -x ) 9 5 8 5 2 10
˜ Á
3
¯ Ë
Ê 1 3ˆ Ê 1 ˆÊ 1 ˆ (f) - 1,470 (g) 61 (h) - 60
(e) Á Ë 4 a + 2¯ ˜ ( -a ) 2 or Á Ë 2 a + 3 ˜Á 2 a - 1 ˜ ¯ 139 7 299
¯Ë
Exercise 8.2
(f) (x + 3)(x – 17) (g) (a + 10)(a + 2) (h) (x – 7)(x – 3)
Review Exercises (a) 17 (b) 2 (c) 2 (d) 3 (e) 375
Multiple Choice Questions 3 29 3 86

1. c 2. a 3. b 4. d 5. a (f) –12 (g) 170 (h) –2 (i) –2.8 (j) –4
Solve Mentally 5 37
True or False (k) –10

1. False 2. False 3. True 4. False 5. True Exercise 8.3
Fill in the Blanks 1. (a) 3 (b) 3 (c) –2 (d) 1 (e) - 1
3 2
1. literals, product, number 2. 5x y 18
2
3. difference 4. a – 4a – 12 5. (2 – 3x – 9y) (f) - 4 (g) 54 (h) –4, 4 (i) - 31 (j) 9
Answer in One Word or a Line 3 41 24 2
1. When an algebraic expression is a product of two or more (k) 36 (l) 5 2. (a) 1 (b) 4
expressions, then each of these expressions is called factor 2
of the given expression. Exercise 8.4
3
2
2 2
2. a – b + a – a b 3. No 4. (x + 3)(x – 1) 1. 43, 27 2. 48, 12 3. 50, 10
2
2
2
2 2
2
5. p – 2pq + q = (p – q) ; (4p – 7q ) 13
Let’s Evaluate 4. 40, 20 5. 71 6. 15, 16 7. 21 8. 62
2
2 4
2
(a) 9xy (x – 3y) (b) x y (2x – 3xy + 4y) 9. 20 coins of ` 1, 60 coins of ` 2, 120 coins of ` 5
2
2
2
(c) y (p + 2q)(y + 1) (d) (x + 4)(x + 2)(x – 2) 10. 20 11. ` 252
(e) (y + a)(y + b) (f) –4xy 12. Aishwarya’s age is 26 years and Karishma’s age is 12 years.
2
2
(g) (3y – 4) (h) 3xy (5x + 6y)(5x – 6y) 1
2
2
(i) (y + y + 1)(y – y + 1) (j) (1 + 8x)(3 – x) 13. 60 14. 10 days 15. 16 kg
2
(k) (x + 4x – y)(x + 5)(x – 1) 2
Thinking Skills 16. 18 km/h and 80 km 17. 40
18. 13 cm and 5 cm 19. 3 h
(a) ( -x 5 )( –5x ) (b) (x + 2)(x – 5)(x – 5) 20. Altitude = 20 cm and base = 12 cm
2
2
(c) (y + y + 3)(y – y + 3) (d) (a + 1)(a – 5)(a – 2)(a – 2) 21. 75 km/h; 79 km/h
(e) ( +x 17y )( – 17x y )(x 2 + 3y 2 ) Brainstorming
4
4
2
2
(f) (x + 5y )(x + 4y )(x + 2y)(x – 2y) 6 × number of bananas + 5 × number of apples = 32
(g) ( 2 2 )( – 2y ) (h) 5 ( 5 +x 4 )( 5 +x ) 2 Since the numbers of bananas and apples are necessarily whole
27 +y
numbers, their respective values are 2 and 4.
376