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Math Help - Domain range

  1. #1
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    Domain range

    Find the largest possible domain for the following funtions:

    a) sqrt x(x-4)

    b) sqrt 2x(x-4)

    Thank you in advance for your help
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  2. #2
    Super Member redsoxfan325's Avatar
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    Quote Originally Posted by Oasis1993 View Post
    Find the largest possible domain for the following funtions:

    a) sqrt x(x-4)

    b) sqrt 2x(x-4)

    Thank you in advance for your help
    Obviously, you can't have a negative sign under the square root.

    So only values of x such that x(x-4) is positive will be in the domain of \sqrt{x(x-4)}.

    Spoiler:
    x(x-4) has two zeroes at x=0 and x=4, so any value of x:0<x<4 will yield a negative value. Thus your domain is \{-\infty,0]\cup[4,\infty).

    Part (b) is identical.
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