To find the domain of a function we want to identify for which x the function y exists.
In this case, for any number x that we plug into the function, it would return a value of y, then the domain are all real numbers.
The cases where the domain is not all real numbers are cases like:
If we plug x = 0, ythe function y does not exists.
In this case, there is no problem with any number, whatsoever
Interval notation:
D = (-∞, ∞)
The notation means "all numbers between minus infinity and positive infinite", in other words, all real numbers