# Infinite Series: Find Function

1. Nov 25, 2005

### MrBailey

Hello all!
I have the following infinite series:

$$\frac{10}{x}+\frac{10}{x^2}+\frac{10}{x^3}+\ldots$$

How would I find a function, f(x), of this series?

I know the series converges for $$\vert x \vert > 1$$

I think the function is: $$f(x) = \frac{10}{x-1}$$

but I'm not sure how to get it.

Thanks,
Bailey

2. Nov 25, 2005

### math-chick_41

why the x-1 in the denominator?
maybe this

$$f_{n}(x) = \frac{10}{x^n}$$

because

$$\sum\frac{10}{x^n}$$

will be what you started with, but I may be worng and/or missing something though.

Last edited: Nov 25, 2005
3. Nov 25, 2005

### Physics Monkey

Hint: factor out a 10/x and see if the remaining series looks familiar to you.

4. Nov 25, 2005

### MrBailey

Ugggh! I'm so blind sometimes...must be all the turkey I ate yesterday. I see the geometric series.

Thanks, PM.

Bailey