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Homework Help: Variation of Parameters on a 1st Order DE

  1. Sep 26, 2010 #1
    1. The problem statement, all variables and given/known data

    Solve xy' - y = x3 (1) by using variation of parameters.

    3. The attempt at a solution

    Solving the homogeneous version of (1) gives

    yh = c1x

    Now we are to seek

    yp = A(x)*x (2)

    from (2)

    y'2 = A'*x +A

    plugging into (1) we have:

    x[A'*x + A] - Ax = x3

    A'x2 = x3

    A' = x

    => A(x) = x2/2 +C2

    =>yp= C2x + x3/2

    Oh ... nevermind! :biggrin:
    Last edited: Sep 26, 2010
  2. jcsd
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