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Thread: Equation of the Tangent...

  1. #1
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    Equation of the Tangent...

    If f(x) = 1/x, find f'(3) and use it to find the equation of the tangent to the curve y = 1/x at the point (3, 1/3).

    I found the slope to be -1/9 but I don't know how to find the equation
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  2. #2
    Like a stone-audioslave ADARSH's Avatar
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    You have done
    $\displaystyle
    f(x)= \frac{1}{x}
    $


    $\displaystyle
    \frac{dy}{dx}= \frac{-1}{x^2}
    $

    And thus got answer $\displaystyle \frac{-1}{9}$


    Now equation of a line ,passing through (a,b),with a slope "m" is given by

    $\displaystyle
    (y-b)=m(x-a)
    $

    So the answer is

    $\displaystyle
    (y-\frac{1}{3}) = \frac{-1}{9} (x-3)
    $
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  3. #3
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    Oh I got it...The answer was just written differently than I had my answer ahah...thanks though
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