Question

if the sum of the first n terms of the AP sn = n^2 + 3n. then the third term of the AP is.

Answer 1

if sn= n^2 +3n

third term= (sum of first third terms)-(sum of first

two terms)

third term= [(3)^(2)+ 3 (3)] - [(2)^(2)+3 (2)]

= [9+9] - [4+6]

=18-10

=8

therefore, third term=8

hope it helps...