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  • May 9, 2009, 10:47 AM
    shacoria14
    More Conic Sections
    identify the vertex,focus,and directrix of the equation
    y^2-4x-2y=3
  • May 9, 2009, 11:06 AM
    Perito
    Quote:

    identify the vertex,focus,and directrix of the equation

    This web site tells a lot about parabolas:

    Parabola - Wikipedia, the free encyclopedia

    (First equation)

    1. axis parallel to the y-axis
    2. vertex: (h,k)
    3. focus: (h,k+p)
    4. directrix: y=k-p



    or

    (Second equation)

    1. axis parallel to the x-axis
    2. vertex: (h,k)
    3. focus: (h,k+p)
    4. directrix: y=k-p


    Your equation is





    The x's are now on the right, the y's on the left side. Let's concentrate on the left side. That's the most difficult since we have a square term. We note that

    but we need a 1 on that side also. Add a 1 to both sides.



    Now factor



    That looks like the second equation with k=1, p=1, h=-1.

    You should be able to figure out the question now.

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