Maths geometric progression examples

Question:

If ratio of sum of first 6 terms of G.P. to sum of first 3 terms of G.P. is 9:1, what is the common ratio of G.P.?

Solve

In the question it is given that

S6/ S3 = 9/1

Therefore, we have to find the value of ‘r’.

{a(r6-1)/(r-1)} / {a(r3-1)/(r-1)} = 9/1

(r6-1) / (r3-1) = 9/1

(r3+1)(r6-1) / (r6-1) = 9/1

r3+1 = 9

r3 = 9-1

r3 = 8

r = 2

Check out more examples of Geometric Progression (G.P.), explained lucidly.

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