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Math Help - Function Range.

  1. #1
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    Function Range.

    Ok so i have this problem , i know this topic has been written about before cos i have read all the info i could find!! But im still stumped on this one.

    The question is y= (x+1)(X-2)

    The answer says domain is all real numbers and rane is all real numers greater than -2.25

    Im lost as to how that -2.25 came up.
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  2. #2
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    Quote Originally Posted by el123 View Post
    Ok so i have this problem , i know this topic has been written about before cos i have read all the info i could find!! But im still stumped on this one.

    The question is y= (x+1)(X-2)

    The answer says domain is all real numbers and rane is all real numers greater than -2.25

    Im lost as to how that -2.25 came up.
    the function is quadratic, hence the graph of y is a parabola that opens upward in this case. the y-value of the vertex of the parabola is the least value in the range.

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

    the vertex is located at x = 0.5, midway between the two roots of the function.

    the y-value of the vertex is y = (0.5 + 1)(0.5 - 2) = (1.5)(-1.5) = -2.25
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  3. #3
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    Huzzahh!! Thank you Skeeter.
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