Results 1 to 2 of 2

Math Help - Laplace Transformation

  1. #1
    Member Altair's Avatar
    Joined
    Jan 2008
    Posts
    87

    Laplace Transformation

    1. e^{-t}.u(t-1)

    My answer \frac{s-1}{e^{s+1}}
    Book's answer \frac{1}{s}

    How ? Can you please show it step by step ?

    2. cost.u(t-{pi})

    Can't start it all together.
    Follow Math Help Forum on Facebook and Google+

  2. #2
    Lord of certain Rings
    Isomorphism's Avatar
    Joined
    Dec 2007
    From
    IISc, Bangalore
    Posts
    1,465
    Thanks
    6
    Quote Originally Posted by Altair View Post
    1. e^{-t}.u(t-1)

    My answer \frac{s-1}{e^{s+1}}
    Book's answer \frac{1}{s}

    How ? Can you please show it step by step ?
    I dont think it is \frac1{s}
    Try to do it from definition:

    x(t) = e^{-t}.u(t-1)
    X(s) = \int_{0}^{\infty} e^{-t} e^{-st}u(t-1) \, dt = \int_{1}^{\infty} e^{-(s+1)t}\, dt = -\frac{e^{-(s+1)t}}{s+1}\bigg{|}_{1}^{\infty} = \frac{e^{-s-1}}{s+1}
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. Laplace Transformation
    Posted in the Differential Equations Forum
    Replies: 1
    Last Post: October 31st 2010, 11:46 PM
  2. Laplace Transformation
    Posted in the Advanced Applied Math Forum
    Replies: 4
    Last Post: October 30th 2010, 09:42 PM
  3. help about Laplace transformation
    Posted in the Differential Equations Forum
    Replies: 1
    Last Post: March 15th 2010, 03:09 AM
  4. Laplace Transformation
    Posted in the Calculus Forum
    Replies: 2
    Last Post: March 25th 2009, 02:35 AM
  5. Laplace Transformation
    Posted in the Calculus Forum
    Replies: 1
    Last Post: May 6th 2008, 11:09 PM

Search Tags


/mathhelpforum @mathhelpforum