Question

in an AP the sum of n terms is 1/2(5n^2+3n).find its 40th term

Answer 1

T40=1/2(5*4.^2 +3*40)
T40=1/2(20^2 +120)
T40=1/2(400+120)
T40=1/2(520)
T40=260

The 40th term of AP is 260

Answer 2

The 40term is 199 which is correct