Which term of the GP 1, 2, 4, 8,.... is 512?
8
9
10
11
Given the GP: 1, 2, 4, 8, ......
⇒a=1,r=2 The nth term of a GP of first term a and common ratio r is given by an=arn−1. Let an=512. Then, 1×2n−1=512. i.e., 2n−1=29 ⇒n−1=9 ⇒n=10