Solve the following equations:
(a) 2(x + 4) = 12    (b) 3(n – 5) = 21
(c) 3(n – 5) = −21    (d) −4 (2 + x) = 8
(e) 4(2 – x) = 8

Solution:

We use the concepts of simple linear equations and fundamental operations like addition, subtraction, multiplication and division to solve the problem.

To solve these equations, transpose the variables on one side and constants on the other side, and simplify them and get the value of a variable.

(a) 2(x + 4) = 12

2x + 8 = 12

2x = 12 - 8

2x = 4

x = 4/2

x = 2

(b) 3(n - 5) = 21

3n - 15 = 21

3n = 21 + 15

3n = 36

n = 36/3 or n = 12

(c) 3(n -5) = - 21

3n - 15 = - 21

3n = - 21 + 15

3n = - 6

n =  - 6/3 or n = - 2

(d) - 4(2 + x) = 8

- 8 - 4x = 8

- 4x = 8 + 8

- 4x = 16

x = - 16/4 = - 4

(e) 4(2 - x) = 8

8 - 4x = 8

-4x = 8 - 8 = 0

or, x = 0

☛ Check: NCERT Solutions for Class 7 Maths Chapter 4

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Video Solution:

Solve the following equations: (a) 2(x + 4) = 12 (b) 3(n – 5) = 21 (c) 3(n – 5) = −21 (d) −4 (2 + x) = 8 (e) 4(2 – x) = 8

NCERT Solutions for Class 7 Maths Chapter 4 Exercise 4.3 Question 2

Summary:

We have solved the following equations: (a) 2(x + 4) = 12; x = 2 (b) 3(n – 5) = 21; n = 12 (c) 3(n – 5) = −21; n = - 2 (d) −4 (2 + x) = 8, x = - 4 (e) 4(2 – x) = 8, x = 0

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