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Assistance with series, please!

  1. Apr 11, 2006 #1
    Compute the sum from k=0 to infinity of (k+1)(x)(1-x)^k.

    I don't have any ideas about how to start this one, except that perhaps it resembles a geometric series? Also we're supposed to use the power series for 1/x which we know to be (1-x)^k. (That's all I could figure out on my own so far) :confused: What I could really use some help with is how to get started, then I should be able to pick it up from there. Thank you SO much for any help!
  2. jcsd
  3. Apr 11, 2006 #2


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    hint: [itex](k+1)(1-x)^k = -\frac{d}{dx}(1-x)^k[/itex]
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