Question

Find:

18th term of the AP √2, 3√2, 5√2, …….

Answer 1

Given A.P. is √2, 3√2, 5√2, …….

First term (a) = √2

Common difference = Second term – First term

= 3√2 – √2

⇒ d = 2√2

We know that, nth term in an A. P. = a + (n – 1)d

Then, 18th term of A. P. = √2 + (18 – 1)2√2

= √2 + 17.2√2

= √2 (1+34)

= 35√2

∴ 18th term of A. P. is 35√2.