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Math Help - Completing the Square

  1. #1
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    Completing the Square

    I have no idea if this is the right place to post this, but here goes:

    x^2 - 4x + 8y + 4 = 0

    If someone could please detail each individual step, that would be awesome.
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  2. #2
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    Quote Originally Posted by saintv View Post
    I have no idea if this is the right place to post this, but here goes:

    x^2 - 4x + 8y + 4 = 0

    If someone could please detail each individual step, that would be awesome.

    You don't have to complete the square if you move things around:

    x^2-4x+8y+4=0

    And let's switch the places of the 8y and the 4

    x^2-4x+4+8y=0

    Now let's factor

    (x-2)(x-2)+8y=0

    (x-2)^2+8y=0
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  3. #3
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    Quote Originally Posted by artvandalay11 View Post
    You don't have to complete the square if you move things around:

    x^2-4x+8y+4=0

    And let's switch the places of the 8y and the 4

    x^2-4x+4+8y=0

    Now let's factor

    (x-2)(x-2)+8y=0

    (x-2)^2+8y=0
    Thank you! Now, how would that be written in the (y-k) = a(x-h)^2 form?
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  4. #4
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    Quote Originally Posted by saintv View Post
    Thank you! Now, how would that be written in the (y-k) = a(x-h)^2 form?

    Well we have (x-2)^2+8y=0

    And you want the x on the other side so lets subtract (x-2)^2 from both sides

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

    8y=-(x-2)^2

    And divide by 8 to get

    y=-\frac{1}{8}(x-2)^2

    In this case k=0
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  5. #5
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    Thank you! :d
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