Arithmetic Progression (C10)

The sum of first n terms of an AP is given by Sn = 2n2 + 3n. Find the sixteenth term of the AP.

Answer

Sn = 2n2 + 3n

S1 = 5 = a1

S2 = a1 + a2 = 14

a2 = 9

d = a2 – a1 = 4

a16 = a1 + 15d

a16 = 5 + 15(4) = 65