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Converging absolutely.

  1. Jan 24, 2007 #1
    1. The problem statement, all variables and given/known data

    heres the equation that will converge conditionally: http://img440.imageshack.us/img440/9945/untitled3jg.jpg [Broken]

    changes to
    An = n/(1 + nLNn)

    2. Relevant equations
    alternating series equation.
    converges conditionally.

    d/dn An = (1-n)/(1+nLNn)^2

    3. The attempt at a solution

    I'm not sure how the first equation changes to the second equation, and then i'm supposed to use l'hopitals rule.

    any help please.
    Last edited by a moderator: May 2, 2017
  2. jcsd
  3. Jan 24, 2007 #2


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    Staff Emeritus
    Science Advisor

    Is the equation in the picture meant to read [tex]\sum_{n=2}^{\infty}\frac{(-1)^nn}{1+nlNn}[/tex]?

    Try to learn LaTex; it's very easy to use. Click on the equation to see the code. The tutorial is here: https://www.physicsforums.com/showthread.php?t=8997
  4. Jan 24, 2007 #3

    Gib Z

    User Avatar
    Homework Helper

    An alternating series converges if it meets two conditions: The last term converges to zero and the terms, ignoring the signs, are non-increasing.

    The 1st one is met easily. for the 2nd check check the derivative, if its negative for positive infinity, then it converges.
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