If the sum of n terms of an AP is given by S n = (2n 2 + 3n), then find its common difference.

Question

Philoid · Accepted Answer

Given: S_n = (2n² + 3n)

To find: find common difference

Put n = 1 we get

S_{1 =} 5 OR we can write

a = 5 …equation 1

Similarly put n = 2 we get

S₂ = 14 OR we can write

2a + d = 14

Using equation 1 we get

d = 4