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Homework Help: Solve e^(3x)+sinh(x)=0 ?

  1. Jul 11, 2010 #1
    1. The problem statement, all variables and given/known data

    Solve the following equation for x:

    [tex]e^{3x}+sinh(x)=0[/tex]


    2. Relevant equations

    None.


    3. The attempt at a solution

    It the same as:

    [tex]e^{3x}+\frac{e^{2x}}{2}-\frac{e^{-2x}}{2}=0[/tex]

    Multiply by 2

    [tex]2e^{3x}+e^{2x}-e^{-2x}=0[/tex]

    Multiply by e^(2x)

    [tex]2e^{5x}+e^{4x}=1[/tex]

    then I stopped.
     
  2. jcsd
  3. Jul 11, 2010 #2
    I think [tex]sinh(x)=\frac{e^{x}}{2}-\frac{e^{-x}}{2}[/tex]
     
  4. Jul 11, 2010 #3
    sinh(x) = 1/2(e^x - e^(-x))

    Looks to me like you should be able to get a quadratic equation out of that...
     
  5. Jul 11, 2010 #4
    ohhhh
    sorry
    :|
    I finished it
    thanks <3
     
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