1.

If the 4th, 10th and 16th terms of a G.P. are x, y and z respectively. Prove that x, y, z are in G.P.

Answer»

Let first term of GP be a and common ratio be r 

As nth term of GP is given as – Tn = arn – 1 

∴ T4 = ar4 – 1 = ar3 Similarly T10 = ar9 

And T16 = ar15 

∴ x = ar3, y = ar9 & z = ar15 

Clearly we observed that x, y, z have a common ratio. 

∴ x,y,z are in GP with common ratio r6.

Hence proved.



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