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Homework Help: A stubborn integral

  1. Jun 5, 2010 #1
    1. The problem statement, all variables and given/known data
    I have to integrate

    [PLAIN]http://img69.imageshack.us/img69/4259/integral1.gif [Broken]

    3. The attempt at a solution

    This is how I did it

    [PLAIN]http://img338.imageshack.us/img338/5508/integral12.gif [Broken]

    wolfram says it is supposed to turnout like this

    [PLAIN]http://img690.imageshack.us/img690/1462/integral13.gif [Broken]

    Where does the extra 2 in the log come from?

    Last edited by a moderator: May 4, 2017
  2. jcsd
  3. Jun 5, 2010 #2


    User Avatar
    Science Advisor
    Homework Helper

    The answers are actually the same, up to a constant -2 ln(2).

    With logarithms this is always tricky, because they satisfy
    [tex]\ln(a \cdot b) = \ln(a) + \ln(b)[/tex]

    Apparently Wolfram Alpha / Mathematica uses some other method to calculate the integral in which the 2 inside the log appear naturally.
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