Domain: The set of all possible input values (commonly the "x" variable) It is the set of all real numbers for which a function is mathematically defined.
[tex]f(x) = \sqrt[1]{x-9} [/tex]
The function has noun defined points nor domain constraints. Therefore, the domain is
[tex]- \infty} \ \textless \ x \ \textless \ \infty}[/tex]
