Question

Sum of infinite number of term of GP is 20and sum of their square is 100. The common ratio of GP is

Answer 1

Answer

Let terms of GP be a, ar, ar2

where a = first term, r = common ratio

S∞ = a/1-r

Therefore, a/1-r = 20

a = 20(1-r)

Also, a2 = 100(1 - r2)

So, the answer is 3/5