JEE Main 2016 Question Paper

Let the G.P. be a,ar,ar2 and termss of A.P are A + d, A + 4d , A + 8d
then

ar2−ar

ar−a

=

(A+8d)−(A+4d)

(A+4d)−(A+8d)

=

4

3

⇒r=

4

3

Alternate Solution:
Let Ap is a,a + d,a + 2d
2nd,5th and 9th terms a + d,a + 4d,a + 8d are in G.P
⇒(a+4d)2=(a+d)(a+8d)
⇒d(8d−a)=0⇒8d=a as d≠0
Hence common ratio of GP

a+4d

a+d

=

8d+4d

8d+d

=

12d

9d

=

4

3