Question

In a GP 5th term and 8th term is 80 and 640 respectively. find GP.

Answer 1

Given
5th term=80=a.r^4
6th term=640=a.r^7
…a.r^7=640
a.r^4.r^3=640
80.r^3=640
r^3=8
r=2
g.p. Series are
5,10,20,40,80,160,320,640……………

Answer 2

look in attachment.

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