Determine the radius of convergence of the given power series

Find the radius of convergence of the given power series:

$$\sum _{n=0}^{ \infty} \frac{(-1)^{n+9} (x-3)^{n+9}}{n+9}$$

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Do you also want people to post their answer, or just to determine it? I should also point that this is not a question. There is no WH-word, and there is no question mark at the end. –  Asaf Karagila Nov 17 '12 at 22:35
Dear Ctrl, Welcome to math.SE. since you are a relatively new user, we wanted to let you know a few things about the site. In order to get the best possible answers, it is helpful if you say what your thoughts on the problem are so far (given that you have already asked two similar questions so far and it would be great if you could learn from those questions); this will prevent people from telling you things you already know, and help them write their answers at an appropriate level. –  user17762 Nov 17 '12 at 22:35
Dear Ctrl, if this is homework, please add "homework" as a tag. Don't worry, people will still help! –  amWhy Nov 17 '12 at 22:40
Try ratio test, make sure to test endpoints. –  Robert Nov 18 '12 at 0:52
Hint: Note that this series has the same convergence radius as the following series: $$x^9\cdot\sum_{n=0}^\infty\frac{(-1)^{n+1} x^n}{n+9}$$