NCERT Solution class 7 Mathematics EXERCISE- 4.2
CHAPTER – 4
EXERCISE – 4.2
Q1. Give first the step you will use to separate the variables and then solve the equation:
(i) x – 1 = 0
SOLUTION:-
x-1 +1 = 0 +1
= x = 1
(b) x + 1 = 0
SOLUTION:-
= x + 1 – 1 = 0 – 1
= x = -1
(c) x – 1 = 5
SOLUTION:-
= x – 1 + 1 = 5 + 1
= x = 6
(d) x + 6 = 2
SOLUTION:-
= x – 1 + 1 = 5 + 1
= x = 6
(d) x + 6 = 2
SOLUTION:-
= X + 6 – 6 = 2 – 6
= X = -4
(E) y – 4 = -7
SOLUTION:-
= y – 4 +4 = -7 + 4
= = y = -3
(f) y – 4 = 4
SOLUTION:-
= y – 4 + 4 = 4 + 4
= y = 8
(g) y + 4
SOLUTION:-
= Y +4 – 4 = 4 – 4
= Y = 0
(H) y + 4 = -4
SOLUTION:-
= y + 4 – 4 = -4 – 4
= Y = -8
Q2. Give first the step you will use to separate the variable and then solve the equation:
(a) 3 L = 42
SOLUTION:-
= L = 42/3
= L = 14
(B) B/2 = 6
SOLUTION:-
B = 6 X 2
B = 12
(C) P/7 = 4
SOLUTION:-
P = 4 X 7
`P = 28
(d) 4x = 25
SOLUTION:-
= x = 25/4
= x = 5.1
(e) 8y = 36
SOLUTION:-
= y = 36/8
= y = 4.5
(f) z/3 = 5/4
Solution:-
= z = 15/4
= z = 3.75
(g) a/5 = 7/15
SOLUTION:-
= a = 35/15
= a = 7/3
= a = 2.9
(h) 20t = -10
SOLUTION:-
= t = = -1/2
Q3.Give the steps you will use to separate the variable and then solve the equation:
(a) 3n – 2 = 46
SOLUTION:-
3n = 46 +2
3n = 48
n = 48/3
n = 16
(b) 5m + 7 =17
SOLUTION:-
5m = 17 – 7
5m = 10
m = 10/2
m = 5
(c) 20p/3 = 40
SOLUTION:-
= 20p = 120
= p = 120/20
= p = 6
(d) 3p/10 = 6
SOLUTION:-
= 3p = 6 x 10
= 3p = 60
= p = 60/3
= p = 20
Q4. Solve the following equations:
(a) 10p=100
SOLUTION:-
= 10p = 100
= p = 100/10
= p = 10
(b) 10p + 10 = 100
SOLUTION:-
= 10p = 100-10
= 10 p = 90
= p = 9
(c) p/4 = 5
SOLUTION:-
= p = 20
(d) –p/3 = 5
SOLUTION:-
= -P = 15
(E) 3p/4 = 6
SOLUTION:-
= 3p = 24
= p = 24/3
= p = 8
(f) 3s = -9
SOLUTION:-
= s = -9/3
= s = -3
(g) 3s + 12 = 0
SOLUTION:-
= 3s = -12
= s = -4
(h) 3s = 0
SOLUTION:-
= s = 0
(i) 2q = 6
SOLUTION:-
q = 6/2
q = 3
(j) 2q – 6 = 0
SOLUTION:-
= 2q = 6
= q = 6/2
= q = 3
(k) 2q + 6 = 0
SOLUTION:-
= 2q = -6
= q = -6/2
= q = -3
(i) 2q + 6 = 12
SOLUTION:-
= 2q = 12-6
= 2q = 6
= q = 6/2
= q = 3