If the 2^nd, 5^th and 9th terms of a non-constant A.P. are in G.P., then the common ratio of this G.P. is:

• 8/5

• 4/3

• 1

• 1

B.

4/3

Let a be the first term and d be a common difference. Then, we have a+d, a+4d, a+8d in GP,

ie. (a +4d)² = (a+d)(a+8d)

⇒ a² +16d² +8ad = a² +8ad +ad +8d²

⇒ 8d² = ad
8d =a  [∴ d≠0]
Now, common ratio,