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Homework Help: Trying Integration by Parts

  1. May 3, 2010 #1
    1. The problem statement, all variables and given/known data

    ∫e^-x cos(2x)dx

    2. Relevant equations
    I'm trying integration by parts and I set u=e^-x and dv=cos(2x)

    3. The attempt at a solution
    I got to where ∫udv= (e^-x)(1/2 sin(2x))+1/2∫sin(2x)e^-x
    I am trying to run through a second time and I'm a little stuck
  2. jcsd
  3. May 3, 2010 #2


    User Avatar
    Homework Helper

    Take ∫sin(2x)e-x dx separately.

    u= e-x du=?

    dv= sin(2x)dx v =?
  4. May 3, 2010 #3


    Staff: Mentor

    Continuing as you are, you should get an equation with ∫e^-x cos(2x)dx on one side and the same on the other side, plus some other terms. Move both integral terms to one side of the equation and solve algebraically for the integral.
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