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Homework Help: Laplace transform using properties

  1. Dec 20, 2011 #1
    1. The problem statement, all variables and given/known data
    Find the laplace transform of
    f(t)=(t-5)e[itex]^{-17(t-5)}[/itex]u(t-5)

    3. The attempt at a solution

    The answer I got was [itex]\frac{e[itex]^{-5(s+17)}[/itex]}{(s+17)^{2}}[/itex].
    I thought I finally understood the process, but when I plugged it into wolfram alpha, the answer I got was different...

    http://www.wolframalpha.com/input/?i=laplace+transform+of+((t-5)e^(-17(t-5)))*theta(t-5)

    Shouldn't the "s" in the exponent be "s+17" or is my understanding really wrong??
     
  2. jcsd
  3. Dec 20, 2011 #2

    vela

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    Wolfram Alpha's answer is the correct one.
     
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