Question

If the sum of first n terms of an a.p is given by sn = 4n^2-3n then find the nth terms os an A.P

Answer 1

Sn=4n2-3n

Sn-1=4(n-1)2-3(n-1)

=4(n2-2n+1)-3n+3

=4n2-8n+4-3n+3

=4n2-11n+7

Sn-Sn-1=4n2-3n-(4n2-11n+7)

=4n2-3n-4n2+11n-7

=8n-7

Therefore, the nth term is 8n-7.