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Homework Help: Log equations

  1. Oct 8, 2006 #1
    I am a little stuck how to solve this equation

    e^x = 5-2x???

    I did ln e^x = ln (5-2x)

    x = ln(5-2x) / ln e
    but iam not sure how to bring the other x around to the side with the x to solve the equation??????
     
  2. jcsd
  3. Oct 8, 2006 #2

    HallsofIvy

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    Science Advisor

    You can't with the "usual" functions. Since you have x both in the exponent and not, you would have to do a numerical solution or use "Lambert's W function", the inverse function to f(x)= xex.
     
  4. Oct 8, 2006 #3
    how would you go about doing a numerical solution?
     
  5. Oct 9, 2006 #4
    Why not try it graphically and then do some approximating to find the intercept, e.g. decimal search. This would work if you did not need a highly accurate solution, e.g. in terms of Pi.

    The Bob (2004 ©)
     
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