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Math Help - exponential equation

  1. #1
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    exponential equation

    I am practicing for my exams need help to see if i'm doing the right thing. Thank you







    Determine the values of x in the following exponential equations:

    (a)3x27x + 81 = 729


    (b)(23x)x + 32 = 1/256



    5. Solve the following equations:

    (e) y = 2x (f) 2x y + 2 = 0
    y = x2 + 1 4x + y 5 = 0

    (g) x y = 0
    5x 3y = 10

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  2. #2
    Senior Member vincisonfire's Avatar
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    Do you mean
     {3 \cdot x}^{27 \cdot x} +81 = 729 ???
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  3. #3
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    Quote Originally Posted by Michelle Belford View Post
    I am practicing for my exams need help to see if i'm doing the right thing. Thank you

    Determine the values of x in the following exponential equations:

    (a)3x27x + 81 = 729

    (b)(23x)x + 32 = 1/256
    (a)3x27x + 81 = 729

    did you mean the exponential equation 3^x \times 27^x +81 = 729  \;\;?
    Last edited by Shyam; October 22nd 2008 at 05:18 PM.
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  4. #4
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    REPLY TO SHYMAN ?

    YES U R CORRECT
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  5. #5
    Senior Member vincisonfire's Avatar
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    3^x \times 27^x +81 = 729
    3^x \times 3^{3\cdot x} = 729 - 81
    3^{x+3\cdot x} = 648
    {4\cdot x} \cdot ln(3) = ln(648)
    x = \frac{ln(648)}{4 \cdot ln(3)}
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