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Math Help - Differencial equation problem?

  1. #1
    Newbie
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    Oct 2011
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    Differencial equation problem?

    6y''+y'-y=x^2-x+4e^(-3t)
    "find a particular solution"

    I get
    -4*e^(-3t)-t^2-t-13
    or
    39/50*e^(-3t)-t^2-t-13
    but apparently they both are wrong?
    Can someone here help me confirm if they are right or wrong?

    EDIT: I'm an idiot.
    Last edited by stupidoldman; October 17th 2011 at 05:31 PM.
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  2. #2
    A Plied Mathematician
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    Re: Differencial equation problem?

    Several comments:

    0. You are mixing independent variables there. Are they all x's? Or all t's?
    1. Checking to see if your guess works is usually fairly straight-forward. Just plug your solution into the DE and see if it satisfies it.
    2. Assuming your RHS is all x's, I would try a particular solution of the form y_p = A x^2 + B x + C + D exp(-3x).
    3. Finally, you spell it "differential", not "differencial".
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