Question

The first term of a g.p is twice it's common ratio, find the sum of the first two term of the progression, if it's sum to infinity is 8

Answer 1

a = 2r, so r = a/2

a/(1-r) = 8
a/(1-a/2) = 8
a = 8-4a
a = 8/5

So, the sequence is

8/5, 32/25, 128/125, ...