The domain of a function is the set of all numbers that the independent variable can assume and have the function be defined. In your case, it doesn't matter what value you select for , the function will always be defined because it always has a value of -1. Therefore, the domain of is all real numbers. There are a couple of ways to express that, other than just saying it:
In set builder notation:
In interval notation:
The range of a function is the set of all values that the function can assume for every possible value in the domain. In this case, for every real number input to your function, the value of the function is -1. Therefore the range is the number -1.
