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Math Help - Please help, Finding f o g and g o f ?

  1. #1
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    Please help, Finding f o g and g o f ?

    Hello all, I need the answer to the following equation, I'd very much appreciate it!

    find A)f o g and b) g o f given F(x) = square root of (x+4) and g(x) = x^2 - 4



    if you could give me the answer and briefly go over the steps in finding the equation, i'd be glad!
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  2. #2
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    Re: Please help, Finding f o g and g o f ?

    Swishh

    do you understand what fog and gof means....it is easy...just replace in the place of x the other function
    ie. gof(x): get g(x) as function and instead of x replace (substitute) the whole f(x) as it is......same for fog revise the chaper of the composite functions pls.

    MINOAS
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  3. #3
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    Re: Please help, Finding f o g and g o f ?

    If, for example, f(x)= 3x^2- x+ 6 and g(x)= x^3+ 2x then fog(x)= f(x^3+ 2x)= 3(x^3+ 2x)^2- (x^3+ 2x)+ 6[/tex] and gof(x)= g(3x^2- x+ 6)= (3x^2- x+ 6)^3+ 2(3x^2- x+ 6).
    Thanks from swishh
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    Re: Please help, Finding f o g and g o f ?

    bump. are both f o g and g o f = to x?
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    Re: Please help, Finding f o g and g o f ?

    Quote Originally Posted by swishh View Post
    are both f o g and g o f = to x?
    You must realize that \sqrt{x^2}=|x|\ne x~.
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    Re: Please help, Finding f o g and g o f ?

    Quote Originally Posted by Plato View Post
    You must realize that \sqrt{x^2}=|x|\ne x~.
    is this for f o g or g o f?

    is the answer for f o g and g o f both x, or is it absolute value of x?
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    Re: Please help, Finding f o g and g o f ?

    Quote Originally Posted by swishh View Post
    is this for f o g or g o f?
    is the answer for f o g and g o f both x, or is it absolute value of x?
    You answer your own question by looking at two examples:

    f(g(-3))=~?~~\&~~g(f(-3))=~?
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