Results 1 to 3 of 3

Math Help - Laplace Transform of Integral

  1. #1
    Newbie
    Joined
    Sep 2009
    From
    Michigan
    Posts
    20

    Laplace Transform of Integral

    Find f(t) if L(f) = 5/[s**2 - 5s]

    From this, I can see components of cosh(SQRT(5)t), but the answer in the back of the book is cosh(SQRT(5)t) - 1.

    Just not quite seeing how to get there. If anyone can provide guidance (not necessarily the full answer), it will be much appreciated.
    Follow Math Help Forum on Facebook and Google+

  2. #2
    Flow Master
    mr fantastic's Avatar
    Joined
    Dec 2007
    From
    Zeitgeist
    Posts
    16,948
    Thanks
    5
    Quote Originally Posted by dsprice View Post
    Find f(t) if L(f) = 5/[s**2 - 5s]

    From this, I can see components of cosh(SQRT(5)t), but the answer in the back of the book is cosh(SQRT(5)t) - 1.

    Just not quite seeing how to get there. If anyone can provide guidance (not necessarily the full answer), it will be much appreciated.
    f(t) = 5 L^{-1} \left[ \frac{1}{s(s - 5)} \right] = 5 L^{-1} \left[ \frac{A}{s} + \frac{B}{s - 5} \right] = 5 (A + B e^{5t})

    where you should be able to get the constants A and B arising from the partial fraction decomposition.
    Follow Math Help Forum on Facebook and Google+

  3. #3
    Newbie
    Joined
    Sep 2009
    From
    Michigan
    Posts
    20
    I now see where I messed up...right at the beginning.

    Instead of "Find f(t) if L(f) = 5/[s**2 - 5s]"...

    ...It should have been "Find f(t) if L(f) = 5/[s**3 - 5s]"

    I now understand how to work it out.
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. Replies: 5
    Last Post: March 22nd 2014, 03:53 PM
  2. Laplace transform to calculate an integral.
    Posted in the Differential Equations Forum
    Replies: 7
    Last Post: May 11th 2011, 07:38 AM
  3. Laplace transform and Fourier transform what is the different?
    Posted in the Advanced Applied Math Forum
    Replies: 8
    Last Post: December 29th 2010, 10:51 PM
  4. Solving integral equations using Laplace transform
    Posted in the Advanced Applied Math Forum
    Replies: 1
    Last Post: August 18th 2010, 06:19 AM
  5. Laplace transform integral problem
    Posted in the Calculus Forum
    Replies: 0
    Last Post: November 29th 2009, 12:21 PM

Search Tags


/mathhelpforum @mathhelpforum