Question

If Sn, the sum of first n terms of an A.P. is given by Sn = 5n2 + 3n, then find its nth term and common difference.

Answer 1

S1=5×1²+3×1
=5+3
=8

S2=5×2²+3×2
=20+6
=26

2nd term= 26-8
=18

d= 18-8
=10

AP is 8,18,26,34......