The domain is any x-value that produces a real y-value. In this function every x-value equals -4, so the domain is all the real numbers. We represent that with this notation:
\(Domain:{\{x∈\rm I\!R\}}\)
The range is the set of all the valid outputs. In this equation, the only valid output is -4. We represent that like this:
\(Range:{\{f(x)∈\rm I\!R|f(x)=-4\}}\)
To summarize, x can be any real number, and y=-4.