Question

The sum of the first n terms of an AP is (3n² + 6n). Find the nth term and the 15^th term of this AP.

Answer 1

Let S_n denotes the sum of first n terms of the AP.

Putting n = 15, we get

a₁₅ = 6 x 15 + 3 = 90 + 3 = 93

Hence, the n^th term is (6n + 3) and 15^th term is 93.