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Logarithms in Systems of Equations

  1. Jan 22, 2013 #1
    1. The problem statement, all variables and given/known data
    Consider the system...

    [itex]y=e^{-x}+1 \\ y=2+lnx[/itex]

    3. The attempt at a solution
    I don't think there is a "pretty way" (algebraic manipulation) to do this. I simply found the point where the plots intercepted, getting the solution set (0.62745018..., 1.5339409...).

    Is there a better way to do this? For what it's worth, this was for a friend who claims that her math teacher is unreasonable, so I don't know if it does has a fully algebraic approach.

    Edit: For clarity, both have a domain and codomain in the set of real numbers, so there isn't an imaginary part to worry about.
     
    Last edited: Jan 22, 2013
  2. jcsd
  3. Jan 22, 2013 #2

    mfb

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    Staff: Mentor

    In general, there is not. Some equations have an analytic solution which is easy to find (x+e^x = 1 for example), but the general case does not have a nice solution.
     
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