Question

if an A.P Common difference is 3, S27 = 1215. The find the value of first term. please as fast as u can​

Answer 1

Answer:

common difference d=3,

given S27=1215

let the first term a

principle

Sn=n/2[(2a+(n-1)d]

S27=27/2(2a+(27-1)3)

1215=27/2(2a+72)

1215=27a+972

27a=1215-972

27a=243

then a=9