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Homework Help: Inverse Laplace- Partial Fractions with exponential

  1. May 3, 2008 #1
    1. The problem statement, all variables and given/known data
    [e^(-2s)] / (s^2+s-2)
    Find the inverse Laplace transform.

    2. Relevant equations

    3. The attempt at a solution
    I know that I can factor the denominator into (s+2)(s-1). Then I tried to use partial fractions to split up the denominator, but I don't know how to do that with an exponential on the top. Thanks for any help!
  2. jcsd
  3. May 3, 2008 #2
    just write it as exp(whatever)*(1/whatever). Then do partial fractions to get exp(whatever)*(?/a + ?/b). You will see that the exponential will be easy to 'invert' back into the time domain as it corresponds to unit step functions (i believe).
  4. Nov 1, 2008 #3
    Im stuck in the same boat, but trying to get the partial fraction for "(e^[-s] -e^[-2s])/[(s^2)(s+1)]"

    I wasn't too sure what EngageEngage meant.
  5. Oct 14, 2009 #4
    i am having the same problems! never knew there was any issue with partial fractions involving exponential components.

    my question was to get partial fraction from 3e^-2s/(s(s+5)), so i brought down the exponential function to get 3 different fractions with 1/e^2s, 1/s and 1/(s+5).

    But it still doesnt work out.
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