Question

if in sn A.Pthe 24th term is twice the 10th term,prove that 36th term is teice the 1yth term

Answer 1

let the first term of A.P a
& common difference be d
then
a+23d=2(a+9d)
or a+23d=2a+18d
or a=5d...........(1)
then 36th term is a+35d=a+7*5d
=a+7a(from (1))
=8a......(proved)