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Math Help - Complex Fractions

  1. #1
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    Red face Complex Fractions

    Ok so I need desparate help with complex fractions. Specificly the LCD part.i know its probably simple and Im most likely skipping or missing out on some rules but I only need to know specific things to pass the placment test and I atleast want to be placed in the classes I need and not some basic math class that will do nothin but waste my time and money.

    So can anyone help me? I found an awesome site called coolmath.com I love it and it helps but I'm just not quite grasping what I need to do to master complex fractions
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  2. #2
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    Example of one of the questions I need help with is...

    2/x3 + 1/x / x/x-1+ 3/x2-1


    2 1
    ___ + ___
    x3 x
    _______________

    x 3
    ___ + ____
    x-1 x2-1
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  3. #3
    MHF Contributor
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    West Malaysia
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    Quote Originally Posted by grlneedstoluvmath View Post
    Example of one of the questions I need help with is...

    2/x3 + 1/x / x/x-1+ 3/x2-1
     <br />
\frac{2}{x^3}+\frac{\frac{1}{x}}{\frac{x}{x-1}}+\frac{3}{x^2-1}<br />

    I am not sure if u mean this ..

    =\frac{2}{x^3}+\frac{x-1}{x^2}+\frac{3}{x^2-1}

    =\frac{2(x^2-1)+x(x^2-1)(x-1)+3x^3}{x^3(x^2-1)}

    Then simplify it .
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  4. #4
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    Hello, grlneedstoluvmath!

    \frac{\dfrac{2}{x^3} + \dfrac{1}{x}}{\dfrac{x}{x-1} + \dfrac{3}{x^2-1}}
    The LCD of all the denominators is: x^3(x-1)(x+1)


    Multiply top and bottom by the LCD:

    . . \frac{x^3(x-1)(x+1)\left[\dfrac{2}{x^3}+\dfrac{1}{x}\right]} {x^3(x-1)(x+1)\left[\dfrac{x}{x-1} + \dfrac{3}{(x-1)(x+1)}\right]}


    . . = \;\frac{2(x-1)(x+1) + x^2(x-1)(x+1)}{x^4(x+1) + 3x^3} \;= \;\frac{2x^2-2+x^4-x^2}{x^5 +x^4+3x^3}


    . . = \;\frac{x^4+x^2-2}{x^3(x^2+x+3)} \;=\;\frac{(x^2-1)(x^2+2)}{x^3(x^2+x+3)}

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