For this case we must find the domain of the following function:

By definition, the domain of a function is given by all the values for which the function is defined.
In this case, the argument of the expression must be greater than 0 to be defined.

Thus, the domain of the function is given by all the values of x greater than -2.
Answer:
Domain: 
The discriminant is b²-4ac
when the discriminant is 0, there is only one solution.