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Homework Help: Help Algebra 2/Trigonometry Problem

  1. Oct 23, 2003 #1
    I'm having trouble with proving this equation: x=-b\2a
    I am not really familiar with this equation but my trigonometry teacher says it is something from Algebra 2. How can I prove why or how this equation works for finding the x-coordinate?
  2. jcsd
  3. Oct 24, 2003 #2
    Taking into account that its almost midnight, i think i can scrap together an answer.

    you are talking about using a specific equation:

    ax^2 + bx + c ( quadratic)

    however you use this equation:

    f(x) = a(x-h)^2 + k (to put it into an equation that will make it easier to find the vertex of the equation)

    h = -b/2a
    k = c - ah^2 ( im almost positive this is right)

    the vertex will equal (h,k) so if the vertex liex on the x axis u will have an x coordinate of the graph. hope that helps some
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