Question
If 4th, 10th and 16th terms of a GP. are x, y and z respectively, Prove that y, z are in GP.
Solution
Let a be the first term and r be the common ratio of G.P.
Given
...(i)
...(ii)
...(iii)
Multiply (i) and (iii), we get
or or [By using (ii)]
∴ or or x, y, z are in G.P.