as far a domain, you only care about the denominator and radicals.
f(x) = 2 - √x is the denominator, so it can't be 0.
Also x is under a radical, so x can't be negative.
Set the denominator equal to 0 to find the excluded values.
2 - √x = 0
-√x = -2
√x = 2
x = 4, so 4 is an excluded value
The domain is all real numbers greater than or equal to 0, except 4.
[0, 4) U (4, ∞)
0 ≤ x < 4 U x > 4
