Question

How do you find the sum of `Sigma(-2/7)^n` from n `[0,oo)`?

Answer 1

Use the Geometric Series Theorem.

Explanation:

`-2/7` is the common ratio of the Geometric Series in this problem.
Since `|-2/7| < 1`, the geometric series converges, and the sum of such a series -- where r is its common ratio -- is given by

`sum_0^(oo)(r)^n = 1/(1-r)`