The 3rd term of a convergent geomatric progession is the Airthmatic mean of the first and second terms.if the first term is 1 the sum to infinity will be

Answer 1

just use your formulas!

ar^2 = (a + ar)/2
2r^2 = 1+r
(2r+1)(r-1) = 0

Now you have r and a, and S = a/(1-r)

Answer 2

INFINITY!

Answer 3

2/3