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Math Help - finding the range (functions) c3

  1. #1
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    finding the range (functions) c3

    hi everyone im really struggling on this question can anybody help


    find the range of

    f(x)= x(x-3) 0 < x < 3 (should be greater/less than or EQUAL to)

    i have completed the square to get (x - 3/2)^2 - 9/4
    but im unsure where to go from there

    thanks..
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  2. #2
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    Quote Originally Posted by mike--1988 View Post
    hi everyone im really struggling on this question can anybody help


    find the range of

    f(x)= x(x-3) 0 < x < 3 (should be greater/less than or EQUAL to)

    i have completed the square to get (x - 3/2)^2 - 9/4
    but im unsure where to go from there

    thanks..
    Draw the graph. You only want the part from x = 0 to x = 3. f(0) = f(3) = 0 and the turning point is at (3/2, -9/4). The range is clearly -\frac{9}{4} \leq y \leq 0.
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  3. #3
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    ive found the answer out and it says its

    -9/4 < f(x) < 0

    i couldnt get where it was coming from , but by completing the square i got

    (x - 3/2)^2 - 9/4

    but i cant seem to lin it to the answer where the domain is 0 < x < 3

    thanks for the help
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  4. #4
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    i only read the first response before i wrote the reply
    thank you both for the help
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