Question

Choose Correct/Incorrect

(i) In 4x + x – 13 = 7 put x = 4 (Correct/Incorrect)

(ii) In 3x – 8 = 25 put x = 12 (Correct/Incorrect)

(iii) In 7x – 5 = 3x + 7 put x = 3 (Correct/Incorrect)

(iv) In 5x – 7 = 4x + 1 put x = 5 (Correct/Incorrect)

Answer 1

(i) 4x + x – 13 = 7 put x = 4

L.H.S. = 4x + x – 13 = 5x – 13
= 5 x 4 – 13
= 20 – 13 = 7 = RHS

Hence 4x + x -13 = 7 put x = 4 is correct.

(ii) 3x – 8 = 25 put x = 12

LHS = 3 – 8
= 3 x 12 – 8
= 36 – 8 = 28 ≠ RHS

Hence 3x – 8 = 25 put x = 12 is in correct.

(iii) 7x – 5 = 3x +7 put x = 3

7x – 5 = 3x +7
7 x 3 – 5 = 3 x 3 + 7
21 – 5 = 9 + 7
16 = 16
LHS = RHS

Hence 7x – 5 = 3x +7 put x = 3 is correct.

(iv) 5x – 7 = 4x +1 put x = 5

LHS or RHS put x= 5
5 x 5 – 7 = 4 x 5 + 1
25 – 7 = 20 + 1
18 ≠ 21
LHS ≠ RHS

Hence 5x – 7 = 4x + 1 put x = 5 is correct.