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Math Help - Completing the square

  1. #1
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    Completing the square

    Basically got coursework in due tomorrow (10% of final marks, kinda a homework sheet).

    y=x^2+8x+1 <-- Complete the square and find the min point.

    (x+4)^2-15=x^2+8x+1

    Got: min point (-4,-15)
    Just wondering if the x is a minus or not, because its squared (Above).

    y=3x+6x+11 <-- Complete the square and find the min point.
    And Im not sure how to go about this, because of the 3x.

    Cheers! jD.
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  2. #2
    A riddle wrapped in an enigma
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    Quote Originally Posted by Backlock View Post
    Basically got coursework in due tomorrow (10% of final marks, kinda a homework sheet).



    Just wondering if the x is a minus or not, because its squared (Above).



    And Im not sure how to go about this, because of the 3x.

    Cheers! jD.
    y=(x+4)^2-15

    The vertex is (-4, -15), so the minimum is the y value. Minimum point is the vertex.

    In your second one,

    y=3x^2+6x+11

    y=3(x^2+2x+1)+11-3

    y=3(x+1)^2+8

    Vertex is at (-1, 8)
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  3. #3
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    Thanks alot, I ended up with (1/3 , 8) Saved a me few marks
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