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Math Help - Parabola Finding the focus

  1. #1
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    Parabola Finding the focus

    write the standard form of the equation
    x^2-4x+8y+12=0
    find the focus

    i have it down to (x-2)^2=-8(y-8) is this right?
    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
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  2. #2
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    Quote Originally Posted by markwjak View Post
    write the standard form of the equation
    x^2-4x+8y+12=0
    find the focus

    i have it down to (x-2)^2=-8(y-8) is this right?
    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
    x^2-4x+4=-8y-8

    (x-2)^2 = -8(y+1)
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  3. #3
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    Quote Originally Posted by skeeter View Post
    x^2-4x+4=-8y-8

    (x-2)^2 = -8(y+1)

    so how would you find the focus of the equation now -8=4a so a=-2 ?
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  4. #4
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    Quote Originally Posted by markwjak View Post
    so how would you find the focus of the equation now -8=4a so a=-2 ?
    Yes, but a= 2 is not the focus. The focus is a point, not a number.
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