Final answer:
a) f(Z) = 2Z. b) Not enough information to determine f(N). c) f(R) represents the set of all real numbers.
Step-by-step explanation:
a) To find f(Z), we substitute Z into the function f(x) = 2x. So, f(Z) = 2Z.
b) To find f(N), we substitute N into the function f(x) = 2x. However, it is unclear what N represents, so we cannot determine the value of f(N) without further information.
c) The domain of f(x) is the set of real numbers, so f(R) represents all possible outputs when the input is any real number. Therefore, f(R) represents the set of all real numbers.