# Math 11 Edublog Post #2

This week the thing that I learned in class that I found the most interesting was how to find the sum of an infinite geometric series. For a geometric series to be infinite the common ratio (r) has to be greater than -1 and less than 1 (Ex. 0.89).

The equation to find the sum of an infinite geometric series you have to use the following equation

$a/1-r$

if we had a series with the 1st term being 3 and the difference being 0.72 then the equation would look like the following.

$3/1-0.72$

$3/-.28$

$-10.71$