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Math Help - Composite function proplem

  1. #1
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    Composite function proplem

    Determine if the FoG is defined, if it is not find the resriction of Go so that FoG is defined.

    - f and g have domain of 0 to infinity
    f(x)= root x
    g(x)=3-2x

    please help urgent

    Edit: well my main problem is that i dont know how to find out if the 2 compostie functions is defined or not, pls explain that part for me thanks
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  2. #2
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    f=\sqrt{x} so f isn't definied for negative numbers, but luckily the domain is the non-negative numbers

    g is defined for all real numbers, so we're good there

    so f(g)=\sqrt{3-2x} but we need 3-2x to be non negative, so you must restrict the domain of g to ensure that 3-2x only spits out non negative numbers
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  3. #3
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    so is there like general rule so that we can know if the 2 functions are defined ?
    so the restriction of domain g would be from 3/2 to infinity ?

    i got that answer but on the back of the book it says 0 to 3 is the restriction domain for g'
    Last edited by kevintrung; September 14th 2009 at 04:47 PM.
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  4. #4
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    some1 help ?
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