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Math Help - solving equation

  1. #1
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    solving equation

    751 =\pi \* 75^2 [-1/(x+30) + 1/x]

    Find the value of x.

    I already tried expanding, but it just makes things worse.

    According to my calculator, x should be about 15.5, but I got no way to prove it!
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  2. #2
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    751 = 75^{2}\pi \left(\frac{1}{x} - \frac{1}{x+30}\right)

    Is this your equation?

    \frac{751}{75^{2}\pi} = \frac{1}{x} - \frac{1}{x+30}

    \frac{751}{5625\pi} = \frac{x+30 - x}{x(x+30)}

    \frac{751}{5625\pi} = \frac{30}{x^{2} + 30x}

    Cross multiply and keep going
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  3. #3
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    Quote Originally Posted by iphysics View Post
    751 =\pi \* 75^2 [-1/(x+30) + 1/x]

    Find the value of x.

    I already tried expanding, but it just makes things worse.

    According to my calculator, x should be about 15.5, but I got no way to prove it!
    You would do better to post your whole problem, rather than post it in pieces. It would make it easier to help you and provide more continuity for you (and others) trying to put the pieces together.

    -Dan
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