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Homework Help: Parabola General to standard form

  1. Jan 24, 2010 #1
    1. The problem statement, all variables and given/known data
    write the standard form of the equation
    x^2-4x+8y+12=0
    find the focus
    2. Relevant equations



    3. The attempt at a solution
    i have it down to (x-2)^2=-8(y-8)
    i'm not sure if you have to multiply the -8 on the right side of the equations by 4 since the focus is 1/4a
     
    Last edited: Jan 24, 2010
  2. jcsd
  3. Jan 24, 2010 #2
    (x-2)^2=-8(y-8)

    let x' = x-2
    let y' = y-8

    So, x^2 = -8y'
    or y' = -(1/8)*x^2

    This is it in standard form. To plot it, the vertex of the parabola will be (2, 8) and it will look like an upside down 'U'.
     
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