# Math Help - Simple Power Series Question

1. ## Simple Power Series Question

Is this sufficient for the question asked? or does that extra -1 make it less of a power series?

Thanks!

2. Originally Posted by davismj

Is this sufficient for the question asked? or does that extra -1 make it less of a power series?

Thanks!
I think you're missing a negative sign. $\frac{1+z}{1-z}=-\left(1+\frac{2}{1+z}\right)$...actually...two.

3. Originally Posted by Drexel28
I think you're missing a negative sign. $\frac{1+z}{1-z}=-\left(1+\frac{2}{1+z}\right)$...actually...two.
I'm sorry, but that doesn't really help (except I see my typo!)

From what I can tell, you've rewritten the original expression as

$\frac{1}{1-z} + \frac{z}{1-z}$ and of course $\frac{1}{1-z}$ is $\sum_{n=0}^{\infty}z^n$

Not sure where you're getting the negative sign from, though.