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Homework Help: Can't solve this integral

  1. Sep 20, 2010 #1
    1. The problem statement, all variables and given/known data

    Find the integral, I , of the followin' function.

    2. Relevant equations

    [tex]\int \frac{dx}{4 - lnx}[/tex].

    3.Attempt

    U = sqrt(lnx)
    dx = 2xlnx du

    Therefore

    [tex]\int \frac{2xlnxdu}{4 - U^2}[/tex].

    Integration of this f(x) failed

    These are all integrals we have dealt with

    http://www.mathwords.com/i/integral_table.htm
     
    Last edited: Sep 20, 2010
  2. jcsd
  3. Sep 20, 2010 #2

    gabbagabbahey

    User Avatar
    Homework Helper
    Gold Member

    There is no closed-form solution in terms of elementary functions, but if you use the substitution [itex]u=4-\ln(x)[/itex], you can express the integral in terms of the special function called exponential integral function.
     
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