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Homework Help: Method of Undetermined Coef.

  1. Sep 30, 2008 #1
    1. The problem statement, all variables and given/known data

    Find particular solution for
    y''+2y'+5y = 4(e^-t)cos2t

    2. Relevant equations

    y.c = C(e^-t)cos2t + C(e^-t)sin2t

    3. The attempt at a solution

    y.p (particular solution) = At(e^-t)cos2t + Bt(e^-t)sin2t does not work! Help please!
  2. jcsd
  3. Sep 30, 2008 #2


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    Homework Helper
    Gold Member

    Are you sure your [itex]y_p[/itex] doesn't work? Why don't you show us what you're getting when you plug it into the ODE.
    Last edited: Sep 30, 2008
  4. Sep 30, 2008 #3
    reply oh i figured it out. thank you!
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