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Thread: Exponential Equations

  1. #1
    it's not fun, don't do it Moon Rabbits's Avatar
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    Default Exponential Equations

    How would I solve:

    2 = 6(3 ^ 4f - 2)

    27(3 ^ 3x + 1) = 3


    I've tried a million different methods, but I can't figure out how to get rid of the 6(~) and 27(~) on the outside of the equations without leaving 2/6 or 3/27 on the other side of the equation, which I can't turn into a negative exponent because the numerators are not one.

    I googled for a solution but only came up with answers involving "logs" which I haven't learned to apply yet.

  2. #2
    GO! use leech seed! qwertysaur's Avatar
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    For the first one

    2 = 6(3 ^ (4f - 2))

    (1/3) = 3^(4f - 2)

    3^-1 = 3^(4f - 2)

    -1 = 4f - 2

    f = (1/4)

    Remember, fractions mean negative exponents.

  3. #3
    I'm selling these fine leather jackets Aerith's Knight's Avatar
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    10log1000=3
    10^3=1000

    so 3^4f-2=1/3

    3log(1/3)=4f-2
    (3log1/3 + 2) / 4 = f

    edit: mine is more usefull.. because you dont need the same number in both exponentials

    27(3 ^ 3x + 1) = 3

    3/27 = 3^ (3x+1)

    3log(3/27) = 3x+1

    [3log(3/27) - 1] / 3 = x


  4. #4
    GO! use leech seed! qwertysaur's Avatar
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    She said she didn't learn to use logs yet, so I showed her how to do the first one without logs, and I think she can do the second one now that she can see how to do it.

  5. #5
    it's not fun, don't do it Moon Rabbits's Avatar
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    *is of the male variety*

    Thanks a lot for your answer qwertyxsora. I didn't even think of reducing the fractions, instead I went through as many complicated answers as I could :rolleyes2

  6. #6
    I'm selling these fine leather jackets Aerith's Knight's Avatar
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    -_- .. well.. i see helping ppl really pays off.. ive learned my lesson.


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