Answer:
x >= -2
Explanation:
For real numbers (like, for graphing or applications) the number inside the square root symbol must be a positive number. So, if x is -3, -4, -5 you will get a negative number inside the square root. If x is -2, you get a zero, which is fine(allowed, no problem) If x is -1, you get a 1 inside there, which is no problem. Any positive number for x yields a positive number inside the square root.
So x must be greater than -2.
Saying what x is or can be is what is "the domain"
Domain: x >= -2
This is set notation.
Interval notation looks like this:
[-2, infinitysymbol)
Simply, x >= -2