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Math Help - How to isolate "R" (from a log equation)

  1. #1
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    How to isolate "R" (from a log equation)

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  2. #2
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    A pretty good attempt, well done!

    I prefer not to introduce the \displaystyle \log

    \displaystyle 25000 = 10000\left(1+\frac{R}{100}\right)^6

    \displaystyle 2.5 =\left(1+\frac{R}{100}\right)^6

    \displaystyle \sqrt[6]{2.5} =1+\frac{R}{100}

    \displaystyle\sqrt[6]{2.5}-1 =\frac{R}{100}

    \displaystyle 100(\sqrt[6]{2.5}-1) =R
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  3. #3
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    Thanks.
    Ah, okay.
    How would I do b), though?
    I tried the same method, but I didn't get 360.5%
    Would I still use 25 000 and 10000, or is that only for the first 6 years?
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  4. #4
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    \displaystyle 25000 = 10000\left(1+\frac{R}{100}\right)^{0.6}

    \displaystyle 2.5 =\left(1+\frac{R}{100}\right)^{0.6}

    \displaystyle (2.5)^{\frac{5}{3}} =1+\frac{R}{100}

    \displaystyle (2.5)^{\frac{5}{3}}-1 =\frac{R}{100}

    \displaystyle 100[(2.5)^{\frac{5}{3}}-1] =R
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  5. #5
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    Thank you.
    I know where I went wrong now.
    Last edited by TN17; December 8th 2010 at 07:06 PM.
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