In an AP it is given that S n = qn 2 and S m = qm 2 . Prove that S q = q 3 .

Question

Philoid · Accepted Answer

Given: S_n = qn² , S_m = qm²

To prove: S_q = q³

Put n = 1 we get

a = q …… equation 1

Put n = 2

2a + d = 4q ……equation 2

Using equation 1 and 2 we get

d = 2q

So

S_q = q³

Hence proved.