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Math Help - 2 tangents to the equation

  1. #1
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    2 tangents to the equation

    I believe I may have found one tangent (with the negative slope, but I cant seem to find the other tangent with the positive slope)
    any help appreciated

    Q.
    Find equations of both lines through the point (2, -3) that are tangent to the parabola y = x^2 + x

    edit. working with it more heres what i got

    y = -x -1
    and
    y = 5x - 4

    can somebody confirm these?
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  2. #2
    TD!
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    Consider an arbitrary point of the parabola with co÷rdinates (a,a▓+a).
    Can you set up the equation of the tangent line through this point?
    Then express that this line has to go through (2,-3), you'll get a quadratic equation in a.
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  3. #3
    TD!
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    Quote Originally Posted by chrisc View Post
    edit. working with it more heres what i got

    y = -x -1
    and
    y = 5x - 4

    can somebody confirm these?
    Confirmed!
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