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Homework Help: Series Question

  1. Apr 30, 2007 #1
    1. The problem statement, all variables and given/known data
    (infinity)sigma(n=4) [ (2 / n) - (2 / (n -1)) ]

    2. Relevant equations
    Harmonic series and ratio?

    3. The attempt at a solution
    It's supposed to converge to -2/3, but, I don't know how.

    The first compare to a harmonic series and we see that goes to 0.

    The second, we use a ratio test or something and then compare it? If we simply take the limit it goes to 0.

    I don't know how to show it.
  2. jcsd
  3. Apr 30, 2007 #2


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    Homework Helper

    Write out the first few terms of the series and see if anything occurs to you.
  4. Apr 30, 2007 #3


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    Science Advisor

    "Telescoping series"
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