Basic Domain and Range help

joeyjon

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Joined
Apr 13, 2011
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35
I can't wrap my mind around this statement...

The domain of f of g consists of the numbers x in the domain of g for which g(x) lies in the domain of f.

Question:
write formulas for f of g and g of f and find the domain and range.

f(x)= the square root of the quantity of x+1
g(x)= 1/x

f of g = square root of the quantity of 1/x +1

= square root of the quantity of (x+1)/x

so the domain can't equal 0 or the formula (x+1)/x >or=0 (but in this case can't be zero.)

but I don't remember now. I think we I am supposed to make a number line with the breaks 0 and the solution of (x+1)/x = 0 (which is -1)

so trying -2 gets +1/2 so that works then try...

-1/2 gets a negative number so it is out

then try 1 gets 2 so it works too.

(-infinity,-2] union (0, infinty)

but I don't think that is right and I don't know how to get the range
 
well wait, that was just a typo , not -2 but -1...
(-infinity,-1] union (0,infinity)

buty I am not confident.
 
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