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Math Help - [SOLVED] trig limits

  1. #1
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    [SOLVED] trig limits

    Hi I am looking for the limit..
    Lim x approach k sin(x-k)/(x^2-k^2)
    I tried L`Hopitals Rule and got f `(x)=cos2k-cos2k
    and g `(x) =2k-2k
    which is (cos2k-cos2k)/(2k-2k)
    answer is suppose to be 1/2k.

    What did I miss?
    Last edited by Neverquit; June 8th 2010 at 11:42 PM. Reason: na
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  2. #2
    MHF Contributor Drexel28's Avatar
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    Quote Originally Posted by Neverquit View Post
    Hi I am looking for the limit..
    Lim x approach k sin(x-k)/(x^2-k^2)
    I tried L`Hospitals Rule and got f `(x)=cos2k-cos2k
    and g `(x) =2k-2k
    which is (cos2k-cos2k)/(2k-2k)
    answer is suppose to be 1/2k.

    What did I miss?
    Don't do that L'hopital stuff....

    Remember that \frac{\sin(x)}{x}\overset{x\to0}{\to}1 and \frac{\sin(x-k)}{x^2-k^2}=\frac{\sin(x-k)}{x-k}\cdot\frac{1}{x+k}..
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  3. #3
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    trig limits

    Hi I got it now
    Last edited by Neverquit; June 9th 2010 at 12:12 AM. Reason: worked it out
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