Finding the Sum of a Series: Proving Solutions

[negatifzeo]

Homework Statement

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?

Homework Equations

The Attempt at a Solution

 

[Dick]

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

 

[negatifzeo]

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