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-   -   Confusion in functions (https://www.askmehelpdesk.com/showthread.php?t=202474)

  • Apr 5, 2008, 07:10 AM
    confusedbuzz
    confusion in functions
    I had to do this question :

    The function f is defined for the domain -3≤ x ≤3
    Find the range of f



    I know we're not supposed to just copy questions we are supposed to do but I tried this and I kept getting the answer 53 ≤ x ≤ 89 which is apparently wrong

    what I did was insert -3 into the function first and get 89 as one end of the domain and then insert 3 into the function and get 53 and I just rotated them around from

    89 ≤ x ≤ 53
    to
    53 ≤ x ≤ 89

    anyway, that's not the answer I'm supposed to get

    can anyone help? Thanks
  • Apr 5, 2008, 12:11 PM
    galactus
    What's the function?
  • Apr 5, 2008, 12:19 PM
    confusedbuzz
    Oh sorry I forgot that

    f(x) = 9(x-1/3)^2 - 11
  • Apr 5, 2008, 12:37 PM
    galactus
    1 Attachment(s)
    Look at the graph. The lowest point occurs at x=1/3(the vertex of the parabola) and the highest occurs at x=-3

    The domain is what you put in, the range is what comes out. -3 and 3 won't necessarily give the minimum or maximum.

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