Answer
The domain is the set of non-negative real numbers.
In interval notation, the domain is: $[0, +\infty)$.
Work Step by Step
In the given function, $x$ is defined as the number of years since publication.
This means that $x$ can be any real number 0 or higher (as there can't be a negative number of years).
Thus, the domain of the function R is the set of non-negative real numbers.
