The domain of the function f(x) = 9 - x is all real numbers since there are no restrictions on the values that x can take in this linear function.
The question asks about the domain of the function f(x) = 9 - x. The domain of a function is the set of all possible input values (x-values) for which the function is defined. For the linear function f(x) = 9 - x, there are no restrictions on the x-values; it is defined for all real numbers. This means that we can substitute any real number for x in the equation without causing any mathematical issues such as division by zero or taking the square root of a negative number. Therefore, the domain of the function is all real numbers.