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Math Help - Solving for X

  1. #1
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    Solving for X

    Sorry I am getting errors with latex so ill post in text form, I am getting an answer but I do not think it is right hopefully someone can tell me where I went wrong.

    2 * (0.1)^(x+1) = 25

    to clarify 2 times 0.1 to the power of x +1 equals 25


    I got :

    2 * x + 1 * log 0.1 = 25

    2 * x * log 0.1 = 24

    x * log 0.1 = 12

    x = 12 / log 0.1

    x = -12

    Any input would be appreciated. Thanks
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  2. #2
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    2 * (0.1)^(x+1) = 25

    First divide both sides by 2.

    (0.1)^(x+1) = 25/2

    Now take logs of both sides
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  3. #3
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    Hello, maca404!

    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

    QUOTE

    2*(0.1)^{x+1} .= .25


    I got: .2 * x + 1 * log 0.1 .= .25
    . . Wow ... This is really wrong!

    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~


    We have: . . .2(0.1)^{x+1} .= .25

    Divide by 2: . .(0.1)^{x+1} .= .12.5

    Take logs: .log(0.1)^{x+1} .= .log(12.5)

    . . . . . . . . . . (x+1)log(0.1) .= .log(12.5)

    . . . . . . . . . . . . . . . . . . . . . . . log(12.5)
    . . . . . . . . . . . . . . . . x + 1 .= .----------
    . . . . . . . . . . . . . . . . . . . . . . . .log(0.1)

    . . . . . . . . . . . . . . . . . . . . . . . log(12.5)
    . . . . . . . . . . . . . . . . . . . x .= .---------- - 1
    . . . . . . . . . . . . . . . . . . . . . . . .log(0.1)

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  4. #4
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    Tattoo this on your wrist: if a^p = b, then p = log(b) / log(a)
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