The domain is the set of input values for which the function is real and defined.
Find non negative values for the radicals.
For y = sqrt(3-x) if x is greater than the 3 the value under the square root would be negative which would result in a non real number.
The answer needs to be x <= 3 ( less than or equal to)
For y = sqrt(3x), if x is less than 0, the number under the sqrt root would be negative resulting in a non real number.
The answer is x >= 0 ( greater than or equal to)
