Page 342 - Start Up Mathematics_7

Answer in One Word or a Line Chapter 8
1. An equation is a condition on the variable. No, its not an
equation. Exercise 8.1
2. If x = k satisfies the linear equation, then it is called its 1. (a) 10 : 1 (b) 6 : 1 (c) 20 : 1 (d) 200 : 1
solution, otherwise not. 2. (a) 5 : 2 (b) 9 : 20 (c) 23 : 1 (d) 1 : 3
3. Transposing a term means shifting an additive term from 1 3
one side of the equation to the other. No, in fact it is cross 3. (a) 75% (b) 12% (c) 17 % (d) 68 %
multiplication. 2 4
4. one 4. (a) 33 : 100 (b) 6 : 25 (c) 3 : 20 (d) 5 : 8
5. Adding a constant on both sides of the equation; 5. (a) 1% (b) 43% (c) 0.5% (d) 93%
subtracting a constant from both sides of the equation; 1
multiplying both sides of the equation by a constant; 6. p = 30 7. 33 % 8. 30% 9. 15, Yes
3
dividing both sides of the equation by a constant. 10. 14.4 kg
Let’s Evaluate 11. (a) School A = 2 students per sq. m,

x x School B = 3 students per sq. m (b) School B
1. (a) 7x + 4 = 39 (b) x + + = 180°
2 2 12. (a) A: 15,000 per month; B: 16,000 per month
2. (a) Divide both sides by 5, Add 2 on both sides (b) Company ‘B’
5(x – 2) = 10 ⇒ x – 2 = 2 ⇒ x = 2 + 2 ⇒ x = 4 Exercise 8.2
1
(b) Subtract from both sides 1. ` 13,184 2. ` 233.75 3. 88,000; 79,200 4. 306
4
1 1 3 5. ` 2,12,000 6. ` 1,440, ` 7,440 7. 2 years
x + = 1 ⇒ x = 1 – ⇒ x =
4 4 4 Review Exercises
1 6 Multiple Choice Questions
3. (a) x = (b) x = −
2 5 1. c 2. c 3. c 4. d 5. a
− 1
4. (a) 4m = –1, 8m + 2 = 0, 2m = 6. d 7. b 8. b 9. a
2
n 1 Solve Mentally
(b) 3n = –2, 9n + 6 = 0, + = 0 True or False
2 3
(Note: Answer of Q. 4 may vary) 1. True 2. True 3. False 4. True

5. 28, 30, 32 6. 50°, 40° 5. True 6. True 7. False
Fill in the Blanks
7. Daughter’s age = 6 years, My age = 30 years
8. length = 40 m, breadth = 20 m 9. 70° 1. qr 2. direct proportion
10. 9 years 11. 25 fruit-bearing trees 3. indirect proportion 4. ` 1,184 5. 20%
Thinking Skills 6. less 7. 450% 8. 25%
1. 18 TV sets Answer in One Word or a Line
2. Science: 6 days, Mathematics: 13 days 1. 260 2. P × R × T
2 x + 20 500 100
3. (a) 6 s (b) s (c) x = 20 m
3 6 3. Remove the % sign and move the decimal two places to
(d) Since cat runs twice as fast as the mouse. Therefore, the left.
it will cover twice the distance in the same time. Profit
4. Yes 5. × 100 6. S.I.
Values and Life Skills C.P.
24 days Let’s Evaluate

Exemplar Problems 1. 152 2. 320 3. 500 minutes 4. 600% 5. 1,500%
7 2 2 1 2
1. d 2. c 3. x = 3 4. 5. False 6. (a) 66 % (b) 125% (c) 3% (d) 162 % (e) 4%
4 3 5 2 5
1 7. (a) 100 (b) 37.5 (c) 13.005 8. 400 9. 12 years
6. False 7. 6 years 8. 4, 8
4
9. ` 13,740 10. 1, 2, 3 11. 72 10. 50%

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