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Math Help - Limit/Derivative Problem

  1. #1
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    Limit/Derivative Problem

    I'm having trouble getting started with a calculus problem, can anyone help me?

    The limit \lim_{x \to 4} \frac{\sqrt{x}-2}{x-4} represents the derivative of a function taken at a point. What function? What point? What is the limit?

    I need help getting started with this problem...
    Last edited by RU2010; August 30th 2010 at 04:34 PM.
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  2. #2
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    Well as x\to 4 the point is x=4

    I get \displaystyle \lim_{x \to 4} \frac{\sqrt{x}-2}{x-4}= \frac{1}{4}

    What methods for taking limits have you been taught?
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  3. #3
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    Sorry, I didn't really explain this problem well. I knew the answer to the acutal limit, and the point, but I'm having trouble figuring out what function this represents the derivative taken at a point of.

    If this limit represents the numerical derivative of 1/4 taken at x=4, what would the original function that I'm taking the derivative of be?

    Thanks?
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  4. #4
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    \displaystyle f'(a) = \lim_{x \to a} \frac{f(x) - f(a)}{x-a}
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  5. #5
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    Makes perfect sense now! Thanks so much!
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