Answer:
all real numbers greater than or equal to 3
Explanation:
There's some ambiguity in your "3/x+2-sqrt x-3." I will assume that you meant:
3
---------- - sqrt(x - 3). Using parentheses often changes everything.
x + 2
Here we see that x cannot = -2, because x + 2 would be zero then. And x must be greater than or equal to 3, so that the input to the sqrt function will be 0 or greater. The domain for f(x) is all real numbers greater than or equal to 3. The prohibition against x = -2 has no bearing on the overall domain of this function.