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Math Help - Solve for x in exponential equation.

  1. #1
    Junior Member
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    Exclamation Solve for x in exponential equation.

    Solve for x: (700)/(1+e^-x)=675


    ok this is what i did i solve it all the way to where i got the natural log like so Ln(e^-x)=Ln(1/27) then i get -Ln(1/27) i plug that into my calculator and got 3.296. but when i plugged 3.296 back into the equation i did not get 675. so im am super stuck. please help.
    Last edited by mr fantastic; November 24th 2009 at 03:41 AM. Reason: Changed post title
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  2. #2
    Super Member bigwave's Avatar
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    700/(1+e^(-3.296)) = 675

    when you pluged back did you do this

    700/(1+e^(-3.296)) = 675

    you may have left out the - in the exponent...
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