# Radius of Convergence

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1. Dec 10, 2016

### belvol16

1. The problem statement, all variables and given/known data

2. Relevant equations
Ratio test.

3. The attempt at a solution

I guess I'm now uncertain how to check my interval of convergence (whether the interval contains -2 and 2)...I've been having troubles with this in all of the problems given to me. Do I substitute -2 back into the original equation and see if it is convergent or divergent?

2. Dec 10, 2016

### PeroK

Yes, you have to check $x= \pm2$ explicitly.

3. Dec 10, 2016

### vela

Staff Emeritus

Either your work's wrong or there's a typo in the problem statement. Look at the exponent of $x$.

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