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Math Help - Math help , paraboalas and tangents

  1. #1
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    Math help , paraboalas and tangents




    If The point P(1, 4) lies on the parabola y = x2 + 3x. What is the slope of the tangent to the parabola at P?

    How do you determine what the tangent is in this case? Thanks
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  2. #2
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    Quote Originally Posted by nosh View Post


    If The point P(1, 4) lies on the parabola y = x2 + 3x. What is the slope of the tangent to the parabola at P?

    How do you determine what the tangent is in this case? Thanks
    Let t denote the tangent to the parabola, m_t the slope of the tangent.

    1. m_t = y'(1)

    From y = x^2 + 3x you get y' = 2x+3 and therefore m_t = 5 at x = 1

    2. Yo have the slope and a point of the line. Use the point-slope-formula to determine the equation of the line:

    y - 4 = 5(x-1) . Solve for y.
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