# Infinite Series

1. Feb 23, 2009

### negatifzeo

1. The problem statement, all variables and given/known data
I'm having trouble finding the sum of a series. I am able to perform the task for "geometric" series, where there is an "a" or an "r" value. But take the following problem for instance:
$$\sum_{n=2}^\infty \frac{1}{4^n}$$
I'm just not sure how to approach this problem and "prove" a solution. I know that since the numbers being added are getting smaller and smaller this sum likely converges, and I suspect it converges at (1/4). But again, how do I show this?
2. Relevant equations

3. The attempt at a solution

2. Feb 23, 2009

### Dick

That is a geometric series. It's (1/4)^n.

3. Feb 23, 2009

### negatifzeo

Ah, indeed it is. I don't know how I missed that, I guess this post can be deleted.

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