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Math Help - Exponential Equations.

  1. #1
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    Exponential Equations.

    Solution to the exponential equation:

    3^2x-1=5


    Solve the logarithmic equation for X:

    ln(2 + X) =1
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  2. #2
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    Quote Originally Posted by aligator0207 View Post
    Solution to the exponential equation:

    3^2x-1=5


    Solve the logarithmic equation for X:

    ln(2 + X) =1
    hi

    (1) 3^{2x}=6

    2x \lg 3=\lg 6

    2x=\frac{\lg 6}{\lg 3}

    .....

    (2) Write in another form : e^1=2+x , e is a constant with value so now you can solve for x
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  3. #3
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    What happened to the (-1) in problem 1? And at the end, do I put that into my calculator?
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  4. #4
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    Hello aligator0207
    Quote Originally Posted by aligator0207 View Post
    What happened to the (-1) in problem 1? And at the end, do I put that into my calculator?
    I suspect that you should have put brackets around the 2x-1 and that the original equation was actually:
    3^{2x-1}=5
    and, if so, the working should be:
    (2x-1)\log3=\log5

    \Rightarrow 2x-1 = \frac{\log5}{\log3}

    \Rightarrow x = \frac12\left(1+\frac{\log5}{\log3}\right)
    =\frac{\log3+\log5}{2\log3}

    =\frac{\log15}{\log9}

    =1.2325
    Grandad
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