Class 7 Simple Equations Ex 4.2

1. Give first the step you will use to separate the variable and then solve the equation.

(a) x – 1 = 0

Solution:-

 x = 0 + 1

 x = 1

(b) x + 1 = 0

Solution:-

x  = 0 – 1

x = – 1

(c) x – 1 = 5

Solution:-

 x  = 5 + 1

 x = 6

(d) x + 6 = 2

Solution:-

 x  = 2 – 6

 x = – 4

(e) y – 4 = – 7

Solution:-

 y  = – 7 + 4

 y = – 3

(f) y – 4 = 4

Solution:-

 y = 4 + 4

 y = 8

(g) y + 4 = 4

Solution:-

 y  = 4 – 4

y = 0

(h) y + 4 = – 4

Solution:-

 y  = – 4 – 4

y = – 8

2. Give first the step you will use to separate the variable and then solve the equation.

(a) 3l = 42

Solution:-

\(l = \dfrac{42}{3}\)

l = 14

(b) \(\dfrac{b}{2} = 6\)

Solution:-

b= 6 × 2

b = 12

(c) \(\dfrac{p}{7} = 4\)

Solution:-

p= 4 × 7

p = 28

(d) 4x = 25

Solution:-

x = \(\dfrac{25}{4}\)

(e) 8y = 36

Solution:-

\(y=\dfrac{36}{8}\)

\(y=\dfrac{9}{2}\)

(f) \(\dfrac{z}{3} = \dfrac{5}{4}\)

Solution:-

\(z = (\dfrac{5}{4}) × 3\)

\( x = \dfrac{15}{4}\)

(g) \(\dfrac{a}{5} = \dfrac{7}{15}\)

Solution:-

\(a = (\dfrac{7}{15})× 5\)

a = \(\dfrac{7}{3}\)

(h) 20t = – 10

Solution:-

\(t= \dfrac{-10}{20}\)

\(x = \dfrac{-1 }{ 2}\)

3. 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

\(n = \dfrac{48}{3}\)

n = 16

(b) 5m + 7 = 17

Solution:-

5m = 17 – 7

5m = 10

\(m = \dfrac{10}{5}\)

m = 2

(c) \(\dfrac{20p}{3} = 40\)

Solution:-

20p= 40 × 3

20p = 120

\(p =\dfrac{120}{20}\)

p = 6

(d) \(\dfrac{3p}{10} = 6\)

Solution:-

3p = 6 × 10

3p = 60

\(p = \dfrac{60}{3}\)

p = 20

4. Solve the following equations.

(a) 10p = 100

Solution:-

\(p = \dfrac{100}{10}\)

= p = 10

(b) 10p + 10 = 100

Solution:-

10p = 100 – 10

10p = 90

\(p = \dfrac{90}{10}\)

p = 9

(c) \(\dfrac{p}{4} = 5\)

Solution:-

p= 5 × 4

p = 20

(d) \(\dfrac{-p}{3} = 5\)

Solution:-

\(p = 5 × (- 3)\)

p = – 15

(e) \(\dfrac{3p}{4} = 6\)

Solution:-

3p = 6 × 4

\(3p = 24\)

\(p = \dfrac{24}{3}\)

p = 8

(f) 3s = – 9

Solution:-

\(s = \dfrac{-9}{3}\)

s = -3

(g) 3s + 12 = 0

Solution:-

3s = 0 – 12

3s = -12

\(s = \dfrac{-12}{3}\)

s = – 4

(h) 3s = 0

Solution:-

\(s = \dfrac{0}{3}\)

s = 0

(i) 2q = 6

Solution:-

\(q = \dfrac{6}{2}\)

q = 3

(j) 2q – 6 = 0

Solution:-

2q = 0 + 6

2q = 6

\(2q = \dfrac{6}{2}\)

q = 3

(k) 2q + 6 = 0

Solution:-

2q = – 6

\(q = \dfrac{-6}{2}\)

q = – 3

(l) 2q + 6 = 12

Solution:-

2q= 12 – 6

2q = 6

\(q = \dfrac{6}{2}\)

q = 3