Question

In an A.P .if Sn =2n^2 +3n; then t4.


answer with steps

Answer 1

since

Sn=2n²+3n,

then
S1=2(1)²+3×1=2+3=5=a,

S2=2(2)²+3×2=8+6=14,

then

common difference d=14-5=9,

therefore,

T4=[5+(4-1)9],

T4=[5+3×9],

T4=5+27=32