Find the sum of Ʃ(3→∞) 3(.4)^(n+2)
Sum of Geometric Series = ao/(1 - r), ao=3, r = .4 = 2/5
The Attempt at a Solution
I thought that I could use the definition of the sum of a geometric series (above) to determine the sum of this equation. So 3/(1-.4) = 5. I believe that somewhere I need to account for the difference in taking the sum of the series from 1 (like I normally would) and 5 (series starts at 3 and the ratio is n+2). But I'm not sure how I do that.