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Math Help - Completing the square [finding a maximum and minimum value]?

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    Completing the square [finding a maximum and minimum value]?

    If I had the quadratic expression of x^2 + 6x - 4, and wrote it as (x + 3)^2 + 5, what would be the minimum and maximum values of this and why?
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    Quote Originally Posted by db5vry View Post
    If I had the quadratic expression of x^2 + 6x - 4, and wrote it as (x + 3)^2 + 5, what would be the minimum and maximum values of this and why?
    The minimum value would be 5. This would occur at x = -3 because a squared value cannot be negative so it will be a minimum when (x+3) = 0.

    The maximum would be infinity
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    When completing the square of x^2+6x-4 I get (x+3)^2-13 since (x+3)^2=x^2+6x+9, so to get from 9 to -4 you need to minus 13.

    Just as a heads up.
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    Quote Originally Posted by db5vry View Post
    If I had the quadratic expression of x^2 + 6x - 4, and wrote it as (x + 3)^2 + 5
    In this case, as Chella pointed out, you have the wrong expression. 9+ 5 is NOT equal to -4.

    what would be the minimum and maximum values of this and why?
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