The domain is asking for all possible inputs or x values for this function. Essentially, if you were to graph it, which x values are covered by the line.
I am assuming the function is m(x) = sqrt(-11-x). Since a square root of a negative number is imaginary, we need to find all cases where (-11-x) is positive. In other words, when (-11 - x) is greater than or equal to 0. We can set up this inequality below.
-11 - x >= 0 (I am using >= to represent > with a line underneath it)
(let's add x to both sides)
-11 >= x
This tells us the domain is where x is less than or equal to -11, as represented below.
x <= -11. This represents the domain of the function m(x).