Question

if the sum of first n terms of an ap is 2n^2+7n. then find its n th term​

Answer 1

Answer:

Sn=2n^2+7n

1st term=S1=a=2+7 (by putting n=1 in Sn)=9

S2=8+14=22 (by putting n=2in Sn)

common difference d= 22-9=13

Therefore nth term=9+(n-1).13

=9+13n-13

=13n-4 Ans