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Math Help - logarithm

  1. #1
    Newbie Zharif93's Avatar
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    logarithm

    5^(2x) + 5^(3x-1) = 150
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  2. #2
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    Are you sure this isn't supposed to be

    5^{2x} \cdot 5^{3x-1} = 150?
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  3. #3
    Newbie Zharif93's Avatar
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    im not sure , my friend ask me this question
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  4. #4
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    5^{2z}= (5^x)^2 and 5^{3x-1}= \frac{(5^x)^3}{5}

    Your equation is (5^x)^2+ \frac{(5^x)^3}{5}= 150. If you let y= 5^x you have y^2+ y^3/5= 150 or the cubic polynomial y^3+ 5y^2= 750. Any rational solution for y must be a factor of 750. I suggest you whack your friend about the ears!
    Last edited by mr fantastic; July 17th 2010 at 03:08 PM.
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