The domain of a function is all of the values of x for which the function is defined. If we substitute 4, the answer is 0. However, when any number smaller than +4 is substituted, the equation becomes:
y = sqrt(negative number) which is undefined. Thus, the domain is
D: x ≥ 4
The range of the function can be determined by the domain. The lowest number the equation will yield is negative infinity because when we take the square root of a positive number, there is one positive root and one negative root. For example, sprt(4) = +2 and -2
Thus, the range is
R: -∞ < y < ∞