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Homework Help: Power series interval

  1. Dec 10, 2007 #1
    For summation from 1 to infinity of x^(n)/[2^(n)*n^(4)]
    - I get the radius is 2 by ration test, but how do I get the interval, just by pluggin in?
  2. jcsd
  3. Dec 10, 2007 #2
    anyone? : )
  4. Dec 10, 2007 #3
    well it's just -1<x<1

    so your R is 2, but before you had x/2


    -2<x<2 (equal to)
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