Question

In an ap 4 th term and 8 th term are in the ratio 1:2 if the 10 th termis 30 find ap

Answer 1

Let,a4=a+3d,a8=a+7d

Also,a4:a8=1:2

=2(a+3d)=1(a+7d)

=2a+6d=a+7d

=2a-a=7d-6d

=a=d

Given,a10=a+9d=30

=d+9d=30

=10d=30

=d=a=3

A.P=3,6,9,.....