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: Nonhomogenous Second Order DE

  1. Mar 9, 2008 #1
    [SOLVED] Nonhomogenous Second Order DE

    1. The problem statement, all variables and given/known data
    [tex]y'' - 2y' - 3y = -3te^{-t}[/tex]

    2. Relevant equations

    3. The attempt at a solution

    Well first I tried
    [tex]Y(t) = Ate^{-t}[/tex]
    [tex]Y(t) = At^2e^{-t}[/tex]
    [tex]Y(t) = At^3e^{-t}[/tex]
    [tex]Y(t) = At^3e^{-t} + Bt^2e^{-t}[/tex]
    but I can't seem to get the correct form.

    Does anyone know what form I need my Y(t) in order to solve this?
  2. jcsd
  3. Mar 9, 2008 #2
    I believe I end up with a term like
    [tex]Ae^{-t} = -3te^{-t}[/tex] which I don't believe I can do anything with?

    In fact, in all the cases I've tried I always seem to get something like [tex]Ae^{-t}[/tex] which never cancels out so I can never equation -3te^{-t} to any of my terms
    Last edited: Mar 9, 2008
  4. Mar 9, 2008 #3
    ah finally got it with [tex]At^2e^{-1}+Bte^{-1}[/tex]
    bah that sucked
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook