Question

The nth term of an A.P. is 7n – 5. Its common difference is ______.

Options

• 2

• 9

• 16

• 7

Answer 1

The nth term of an A.P. is 7n – 5. Its common difference is 7.

Explanation:

Given T_n = 7n – 5;

T_{n – 1} = 7(n – 1) – 5

= 7n – 7 – 5

= 7n – 12

∴ d = T_n – T_{n – 1}

= (7n – 5) – (7n – 12)

= 7n – 5 – 7n + 12

= 7