1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

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.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook