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Math Help - Another fraction simplifying.

  1. #1
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    Another fraction simplifying.

    Sorry I'm crap at this..

    simplify
    1/x^2-1 - 2/x+1

    I expanded x^2-1 then cross multiplied

    which i got -2x+3 / (x+1)(x-1)

    Would that be right? I'm not quite sure on this >< the negative signs screw me up alot.

    I think it might be -2x-1 / (x+1)(x-1)

    Please correct me
    Thanks


    EDIT: can i cancel here? 4+k-1 / (k+3)(k-1)
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  2. #2
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    Quote Originally Posted by icesta1 View Post
    simplify
    1/x^2-1 - 2/x+1
    I can't read this.

    Is it \frac{1}{x^2} - 1 - \frac{2}{x + 1}

    or

    \frac{1}{x^2 - 1} - \frac{2}{x + 1}.


    Please use LaTeX or else put brackets where they're needed.
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  3. #3
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    Quote Originally Posted by Prove It View Post
    I can't read this.

    Is it \frac{1}{x^2} - 1 - \frac{2}{x + 1}

    or

    \frac{1}{x^2 - 1} - \frac{2}{x + 1}.


    Please use LaTeX or else put brackets where they're needed.
    Sorry its the second one.
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  4. #4
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    \frac{1}{x^2 - 1} - \frac{2}{x + 1} = \frac{1}{(x + 1)(x - 1)} - \frac{2(x - 1)}{(x + 1)(x - 1)}

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

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

     = \frac{3 - 2x}{x^2 - 1}.
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  5. #5
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    Quote Originally Posted by icesta1 View Post
    Can i cancel here? 4+k-1 / (k+3)(k-1)
    If it's \frac{4 + k - 1}{(k + 3)(k - 1)} then yes, you can.

    \frac{4 + k - 1}{(k + 3)(k - 1)} = \frac{k + 3}{(k + 3)(k - 1)}

     = \frac{1}{k - 1}.
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