Infinite Series: Find Function

MrBailey
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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
 
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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:
Hint: factor out a 10/x and see if the remaining series looks familiar to you.
 
Ugggh! I'm so blind sometimes...must be all the turkey I ate yesterday. I see the geometric series.

Thanks, PM.

Bailey
 
There are two things I don't understand about this problem. First, when finding the nth root of a number, there should in theory be n solutions. However, the formula produces n+1 roots. Here is how. The first root is simply ##\left(r\right)^{\left(\frac{1}{n}\right)}##. Then you multiply this first root by n additional expressions given by the formula, as you go through k=0,1,...n-1. So you end up with n+1 roots, which cannot be correct. Let me illustrate what I mean. For this...
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