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Math Help - Tangent line to the curve.

  1. #1
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    Tangent line to the curve.

    How do I do the following.

    find the equation of the tangent line to the curve:

    xy^3+xy=14

    At point (7,1).
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    Quote Originally Posted by Zanderist View Post
    How do I do the following.

    find the equation of the tangent line to the curve:

    xy^3+xy=14

    At point (7,1).
    x(y^3+y)=14

    x=\frac{14}{y^3+y}

    Now find \frac{dx}{dy} at y = 1
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  3. #3
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    Quote Originally Posted by Zanderist View Post
    How do I do the following.

    find the equation of the tangent line to the curve:

    xy^3+xy=14

    At point (7,1).
    find \frac{dy}{dx} in terms of x and y, then sustitute 7 for x and 1 for y in the derivative expression to find the slope at that point.
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