# How do you find the sum of the infinite geometric series -2+1-1/2+...?

##### 1 Answer

Dec 22, 2015

#### Explanation:

The formula for the sum of a geometric series is

where

Let's look at the terms to find out what the ratio is. Divide

The ratio is

Indeed, divide

So, let's plug our ratio into the formula:

Be careful here - this is the sum of a series whose first term is the ratio itself. In other words, this is the sum of the series

To get the correct sum, all we need to do is add