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Math Help - Laplace

  1. #1
    Newbie
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    Laplace

    Have a question im not to sure about, hopefully im in the right section.


    d^2M/dt^2 =2delta(t-3)-2delta(t-6)

    M=3 and dM/dt = 0 when t=0

    I have to determine and sketch the function

    So far i've took the lapace
    s^2M-3M =2e^-3s - 2e^-6s is this right??

    any pointers on what to do next
    Last edited by Rainey77; June 10th 2010 at 02:19 AM. Reason: typing error
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  2. #2
    A Plied Mathematician
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    If this is a continuous DE, you need to recheck your Laplace transforms. Taking the Laplace transform of a derivative gives you some initial conditions, not just the transform of the original function. So, if L[f(t)]=F(s), then L[f'(t)]=sF(s)-f(0), and there is an analogous formula for the second derivative.
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  3. #3
    A Plied Mathematician
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    Another note: this question really belongs in the Differential Equations forum.
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