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Convergence radius question

  1. Oct 13, 2009 #1


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    [tex]\sum \frac{n^2}{3^nz^n}\\[/tex]

    [tex]\frac{1}{R}=\lim_{n->\infty}\sqrt[n]{|\sum \frac{n^2}{3^nz^n}|}\\[/tex]

    what to do now?
  2. jcsd
  3. Oct 13, 2009 #2


    Staff: Mentor

    What's the question? Also, I don't believe that your formula for 1/R is correct.
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