# NCERT Class 11 Mathematics Solutions: Chapter 9 – Sequences and Series Miscellaneous Exercise 9 Part 7 (For CBSE, ICSE, IAS, NET, NRA 2022)

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1. If then show that are in G. P.

Answer:

It is given that,

… eq (1)

Also,

… eq (2)

From eq (1) and (2)

So, are in G. P.

2. Let be the sum, the product and the sum of reciprocals of n terms in a G. P. Prove that:

Answer:

Consider the G. P. be

According to the given information,

[Sum of first natural numbers is ]

[ forms a G. P.]

So,