Question

Find the middle term(s) of an A.P. 9, 15, 21, 27,…,183.

Answer 1

a=9 d=(9-15)=-6 let a.p be n terms

then,

tn= 183

9+(n-1)d=183

9+(n-1)-6=183

9-6n+6=183

15-6n=183

6n=183-15

n=168/6=28

n middle term will be 28