Answer:
Domain: x <= 4
Explanation:
The domain is all the x's on the graph or all the x's that can be used in the equation. see image for graph. The graph exists coming from negative infinity (the left side of the graph) and then stops at the point where x is 4. So x must be less than 4 or equal to 4.
Algebraically, if x is bigger than 4, you get a negative number inside the radical (the square root symbol) and that is not allowed. Again we find that x has to be less than or equal to 4.