Class 7, Maths, Chapter 4, Exercise 4.2 Solutions
Q.1. Give first the step you will use to separate the variable and then solve the equation:
(a) x – 1 = 0
(b) x + 1 = 0
(c) x – 1 = 5
(d) x + 6 = 2
(e) y – 4 = – 7
(f) y – 4 = 4
(g) y + 4 = 4
(h) y + 4 = – 4
Ans:
(a) x – 1 = 0
Adding 1 to both sides, we get
⇒ x – 1 + 1= 0 + 1
⇒ x = 1
(b) x + 1 = 0
Subtracting 1 from both sides, we get
⇒ x + 1 – 1 = 0 – 1
⇒ x = -1
(c) x – 1 = 5
Adding 1 to both sides, we get
⇒ x – 1 + 1 = 5 + 1
⇒ x = 6
(d) x + 6 = 2
Subtracting 6 from both sides, we get
⇒ x + 6 – 6 = 2 – 6
⇒ x = -4
(e) y – 4 = -7
Adding 4 to both sides, we get
⇒ y – 4 + 4 = -7 + 4
⇒ y = -3
(f) y – 4 = 4
Adding 4 to both sides, we get
⇒ y – 4 + 4 = 4 + 4
⇒ y = 8
(g) y + 4 = 4
Subtracting 4 from both sides, we get
⇒ y + 4 – 4 = 4 – 4
⇒ y = 0
(h) y + 4 = – 4
Subtracting 4 from both sides, we get
⇒ y + 4 – 4 = -4 – 4
⇒ y = -8
Q.2. Give first the step you will use to separate the variable and then solve the equation:
(a) 3l=42
(b) $\frac{b}{2}=6$
(c) $\frac{\mathsf{p}}{\mathsf{7}}\mathsf{=4}$
(d) 4x=25
(e) 8y=36
(f) $\frac{z}{3}=\frac{5}{4}$
(g) $\frac{a}{5}=\frac{7}{15}$
(h) 20t =-10
Q.3. Give the steps you will use to separate the variable and then solve the equation:
(a) 3n–2=46
(b) 5m+7=17
(c) $\frac{\mathrm{20p}}{\mathrm{3}}\mathrm{=40}$
(d) $\frac{\mathrm{3p}}{10}\mathrm{=6}$
Q.4. Solve the following equations:
(a) 10p=100
(b) 10p+10=100
(c) $\frac{\mathrm{p}}{\mathrm{4}}\mathrm{=5}$
(d) $\frac{\mathrm{-p}}{\mathrm{3}}\mathrm{=5}$
(e) $\frac{\mathrm{3p}}{4}\mathrm{=6}$
(f) 3s=-9
(g) 3s+12=0
(h) 3s=0
(i) 2q=6
(j) 2q-6=0
(k) 2q+6=0
(l) 2q+6=12
