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Homework Help: Stuck on simple derivative, u(t)*t*e^(-5t), urnt?

  1. Feb 18, 2006 #1
    Hello eveyrone, I think my brain just shut down, i'm confused on how i would take the derivative of this function i have circled below:
    http://img100.imageshack.us/img100/1671/lastscan2vi.jpg [Broken]

    I know the chain rule, like if it was
    t*e^(-5t) = e^(-5t) + t*(-5)e^(-5t)
    Last edited by a moderator: May 2, 2017
  2. jcsd
  3. Feb 18, 2006 #2
    [tex](u_2 t e^{-7t})' = u_2' t e^{-7t} + u_2 (e^{-7t} + t (-7)e^{-7t})[/tex]
  4. Feb 18, 2006 #3
    Ahh thank u! I c it now! :biggrin:
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