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Math Help - stationary point

  1. #1
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    stationary point

    im having trouble understanding my textbook.

    Question: Use Calculus to determine any stationary points on the curve
    y=2x+(6/x).

    i found that x= √3.
    the book then explians that
    y=2√3+(6/√3)(√3/√3)

    where does the extra √3/√3 come from?
    Last edited by Derivative of Man; November 16th 2008 at 01:31 AM. Reason: needed to finish off
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  2. #2
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    Quote Originally Posted by Derivative of Man View Post
    im having trouble understanding my textbook.

    Question: Use Calculus to determine any stationary points on the curve
    y=2x+(6/x).

    i found that x= √3.
    the book then explians that
    y=2√3+(6/√3)(√3/√3)

    where does the extra √3/√3 come from?
    They are rationalising the denominator:

    y = 2 \sqrt{3} + \frac{6}{\sqrt{3}} = 2 \sqrt{3} + \frac{6}{\sqrt{3}} \cdot \frac{\sqrt{3}}{\sqrt{3}} = 2 \sqrt{3} + \frac{6 \sqrt{3}}{3} = 2 \sqrt{3} + 2 \sqrt{3} = 4 \sqrt{3}.
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