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Homework Help: Find radius of convergence and interval of convergence for the series

  1. Jul 18, 2013 #1


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    x^n/(2n-1) is the series. It starts at 1 and goes to infinity.

    I did the ratio test on it and got abs.(x)

    So the radius of convergence=1, and then I plugged -1 and 1 into the original series and got that they both converged. But the answer is [-1,1). Why aren't they both hard brackets?
  2. jcsd
  3. Jul 18, 2013 #2


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    Pay special attention to x=1. When you plug it into your series you get ##\sum \frac{1}{2n-1}##.

    You know that diverges...

    Hint : Compare it to something you know diverges already.
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