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Math Help - Trouble with Tangents

  1. #1
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    Trouble with Tangents

    I can't figure out how to solve this problem:
    finf k such that the line is tangent to the graph of the function.
    x^2-kx y=4x=9
    Can someone help me understand this problem?
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  2. #2
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    Quote Originally Posted by alecbyrd View Post
    I can't figure out how to solve this problem:
    finf k such that the line is tangent to the graph of the function.
    x^2-kx y=4x=9
    Can someone help me understand this problem?
    Did you mean that we were to find k, such that  y = 4x + 9 is a tangent to the curve y = x^2 + kx?

    If so, remember that the derivative of a function gives the equation of the tangent of that function.

    If you differentiate  y = x^2 + kx , you get  dy/dx = 2x + k . What you must do is compare this to  y = 4x + 9 in order to find k.
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  3. #3
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    Quote Originally Posted by alecbyrd View Post
    x^2-kx y=4x=9
    Does this equation make sense?
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