NCERT Class 11 Mathematics Solutions: Chapter 9 – Sequences and Series Miscellaneous Exercise 9 Part 6 (For CBSE, ICSE, IAS, NET, NRA 2022)

Glide to success with Doorsteptutor material for IMO : fully solved questions with step-by-step explanation- practice your way to success.

Sum of a Geometric Series

1. A G. P. consists of an even number of terms. If the sum of all the terms is times the sum of terms occupying odd places, then find its common ratio.

Answer:

Consider the G. P. be .

Number of terms

According to the given condition,

Consider the G. P. be

So, the common ratio of the G. P. is .

2. The sum of the first four terms of an A. P. is . The sum of the last four terms is . If its first term is , then find the number of terms.

Answer:

The A. P. be a, .

Sum of first four terms

Sum of last four terms

According to the given condition,

[Since (given) ]

So, the number of terms of the A. P. is