1. ## Series Help

Hey I need help with the following problem:

the series from n=1 to infinity of 12/[(-5)^n)

I know it is a geometric series, and that c=12/-5 and r=-1/5, but i don't understand why

Thanks for the help

2. Originally Posted by luckeyduck
Hey I need help with the following problem:

the series from n=1 to infinity of 12/[(-5)^n)

I know it is a geometric series, and that c=12/-5 and r=-1/5, but i don't understand why

Thanks for the help
$\sum_{n=1}^{\infty}\frac{12}{(-5)^n}=12\sum_{n=1}^{\infty}\left( -\frac{1}{5}\right)^n$

Does this help?