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Math Help - Exponential Equation in Quadratic Form

  1. #1
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    Angry Exponential Equation in Quadratic Form

    I am curious as to how i am to solve and equation with a negative exponent.
    My problem is:
    10e^x-15-45e^-x=0
    We are suppose to use the formula that u=e^x.
    I don't know what to do since there is a negative after the 45.
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  2. #2
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    Re: Exponential Equation in Quadratic Form

    Quote Originally Posted by paigesisco View Post
    10e^x-15-45e^-x=0
    We are suppose to use the formula that u=e^x.
    I don't know what to do since there is a negative after the 45.
    \\10e^x-15-45e^{-x}=0\\10e^{2x}-15e^x-45=0\\2e^{2x}-3e^x-9=0\\(2e^x+3)(e^x-3)=0
    Last edited by Plato; March 11th 2013 at 10:19 AM.
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  3. #3
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    Re: Exponential Equation in Quadratic Form

    Can you explain the method you used so that i can use it on future problems? I am confused on how the x's transfered
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    Re: Exponential Equation in Quadratic Form

    Quote Originally Posted by paigesisco View Post
    Can you explain the method you used so that i can use it on future problems? I am confused on how the x's transfered
    Take the original equation an multiply all terms by e^x.
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