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Homework Help: Difficulty With Integration by Parts

  1. Mar 17, 2010 #1
    1. The problem statement, all variables and given/known data
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    2. Relevant equations



    3. The attempt at a solution What I am unsure of is how to find the derivative of u. Since the original integral is integrating with respect to y, should I be finding the derivative of u with respect to y, and treat the x's as contants?
     
  2. jcsd
  3. Mar 17, 2010 #2
    I think it's possible to solve it in terms of x

    let u=x and dv=e^(-x(1+y))

    then,
    du=1
    and v= [e^(-x(1+y))]/(-(1+y))

    I think it should work

    if you want let
    u=e^(-x(1+y))

    du= -(1+y)*e^(-x(1+y))

    you treat y as a constant and x as a variable
    (I am assuming you want to integrate in terms of x)
     
  4. Mar 17, 2010 #3
    Alrighty then - I'll get to work. Thanks for the direction.
     
  5. Mar 17, 2010 #4

    jav

    User Avatar

    Actually du = dx, also dv=e^(-x(1+y))dx

    You can simplify this problem, by performing a w substitution at the beginning ie. consider w = -x*(1+y). It will make the integration by parts less of a headache.
     
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