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Homework Help: Inverse Laplace help

  1. Jul 29, 2009 #1
    find the inverse laplace transform

    F(s)=(2s+1)/(s^2 -2s+2)

    I have broken it down too 2s/((s-1)^2 +1) + 1/((s-1)^2 +1) , then i got...

    2cos(t) + exp(t)sin(t)

    the book states that

    2exp(t)cos(t) + 3exp(t)sin(t) is the answer? Where did I go wrong?
     
  2. jcsd
  3. Jul 29, 2009 #2
    I'm not sure where you went wrong; I can't find a simple inverse for your first term - which is the one that doesn't match the answers - so I'm guessing that's where your problem is.

    However, look at #16 on this table of transforms:

    http://www.swarthmore.edu/NatSci/ec...nMethods/LaplaceZTable/LaplaceZFuncTable.html

    It's exactly the form for your problem, and you don't even have to break it into two fractions.
     
  4. Jul 29, 2009 #3
    thanks that transform is not on the chart my book uses.
     
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