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Math Help - Help with solving exponential equation

  1. #1
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    Help with solving exponential equation

    I can't figure out how to factor out this quadratic exponential equation

    e^2x+7e^x-3=0

    The answer in the book says it is -0.904 but I don't know how to figure out how to get the answer.

    Thank you
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  2. #2
    Super Member wingless's Avatar
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    Let a = e^x.
    Then a^2 = e^{2x}

    e^{2x} + 7 e^x - 3 = 0

    a^2 + 7a - 3 = 0

    a = \frac{-7\pm \sqrt{49 + 4.3}}{2}

    Then use x = \ln a.....
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  3. #3
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    Thank You!
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