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Homework Help: How to integrate 13e^(-0.2x)sin(x)

  1. Feb 23, 2006 #1
    what is the integral of 13e^(-0.2x) sinx?

    i'm using the solving for the unknown integral method.
    i did this twice (each time i took the integral twice, moved the unknown integral to the same side, and divided by 13.52?? I still cannot figure out what i am doing wrong.

    solve for the diffential. dy/dx = x-4+xy-4y y(0)=4
    how can i move it so that x is on one side and y on the other? what is the integral of xy?
  2. jcsd
  3. Feb 23, 2006 #2
    The RHS is factorable into a function of x and a function of y.
  4. Feb 23, 2006 #3
    nvm the first problem. I solved it.
    the integral =

    12.5e^(-.2x) sinx + 2.5e^(-.2x) cosx
  5. Feb 23, 2006 #4
    oops, its should be a - in between.
  6. Feb 23, 2006 #5
    oops still wrong. this is right: -12.5e^(-.2x) cosx - 2.5e^(-.2x) sinx
  7. Feb 23, 2006 #6
    (x-4)(y+1)! Now i see it, thank you!
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