Question

If the sum of first q terms of an ap is 2q+3q2 find nth term

Answer 1

Given sum of first q terms, Sq = 2q + 3q2

Put q = 1, we get S1 = 2 + 3 = 5

Put q = 2, we get S2 = 2(2) + 3(2)2 = 4 + 12 = 16

Here first term a or t1 = 5

t2 = S2 – S1

= 16 – 5 = 11

Common difference, d = t2 – t1

= 11 – 5 = 6

Hence the common difference is 6