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Homework Help: Integral trouble

  1. Jan 3, 2010 #1
    1. The problem statement, all variables and given/known data
    [tex]\int[/tex][tex]e^{2x}cos(x)dx[/tex]


    2. Relevant equations



    3. The attempt at a solution
    This isn't exactly a homework question, but it's close enough: it's from my old Calculus book (Larson), and I've been stuck on it for awhile. I just need a little hint or something. I've tried a u-substitution and haven't found anything that seems to help, and I've tried integration by parts, but nothing really simplifies--I just end up with an integral that is just as hard as before I try integration by parts. Maybe I'm using these techniques wrong or not seeing something obvious. No other 'harder' integration techniques should be needed (they come later in the book). Thanks!
     
  2. jcsd
  3. Jan 3, 2010 #2

    vela

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    Try integrating by parts twice. You'll eventually end up with a term that looks like the original integral. You can collect terms, so to speak, and solve for the integral.
     
  4. Jan 3, 2010 #3
    Ah! I would've never thought of that. Thanks!
     
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