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Homework Help: Solving Inhomogeneous equation

  1. Feb 18, 2008 #1
    1. The problem statement, all variables and given/known data
    Solve the inhomogeneous equation y'' + 4y = 4 with y(0)=0 and y'(0)=0.

    3. The attempt at a solution

    let Y(t) = A, A being some constant
    Y'(t) = 0
    Y''(t) = 0

    => 4Y(t)=4
    => 4A=4
    => A=1
    => y(t)=1
    But y(0)=0, so that cannot be correct.

    Any tips?
  2. jcsd
  3. Feb 18, 2008 #2


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    Science Advisor
    Homework Helper

    It looks like y is not a constant function; but a variable function that satisfies y'' + 4y = 4 with y(0)=0 and y'(0)=0.
  4. Feb 18, 2008 #3
    Yeah, I saw that, but how could I go about solving it if the right hand side is constant?
  5. Feb 18, 2008 #4
    The function [itex]y(t)=1[/itex] is a particular solution. You have to add this to the general solution of the homogeneous equation. Can you find it?
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