A because one input can have only one output
Answer:

Step-by-step explanation:
The function that we have to study in this problem is

The domain of a function is defined as the set of all the possible values of x that the function can take.
For a square-root function, there are some limitations to the possible value of the argument in the root.
In particular, the argument of a square root must be equal or greater than zero, because the square root of a negative number is not defined.
Therefore, in this case, we have to set the following condition for the domain:

And by solving, we get

which means that the domain of this function is all real numbers equal or greater than 5.
Pretty sure the mean is 5
Answer:
(x+1)^2 + (y-3)^2 = 16
Step-by-step explanation:
The equation of a circle is given by
(x-h)^2 + (y-k)^2 = r^2
Where (h,k) is the center and r is the radius
(x--1)^2 + (y-3)^2 = 4^2
(x+1)^2 + (y-3)^2 = 4^2
(x+1)^2 + (y-3)^2 = 16