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Math Help - Standard Equation of a Parabola

  1. #1
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    Unhappy Standard Equation of a Parabola

    I'm confused why my teacher is using a different form than the book of the standard equation of a parabola.

    Teacher: y - k = (1/(4d))(x-h)^2

    Book: (y - k)^2 = 4p(x - h), p != 0

    Are the two equations the same? Any help is appreciated. Thanks!
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  2. #2
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    Quote Originally Posted by ArcherSam View Post
    y - k = (1/(4d))(x-h)^2
    Multiply both sides of the equation by 4d, i.e. (x - h) = 4d(y - k). If d < 0, then the graph opens down, and if d > 0, then the graph opens up.
    Quote Originally Posted by ArcherSam View Post
    (y - k)^2 = 4p(x - h)
    If p < 0, then the graph opens left, and if p > 0, then the graph opens right.
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  3. #3
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    Thanks! So the two equations are equal. []

    Solution give by johnny!:

    y-k = (1 / (4d))(x -h)^2

    (4d / 1)(y - k) = (4d / 1)(1 / (4d))(x - h)^2

    (x - h)^2 = 4d(y - k)
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