Answer:
x is the input, or independent variable and f(x) is the output, or dependent variable or quantity. f(2) represents the output (y-value) when x = 2. The value of f(2) is 2.
Step-by-step explanation:
If the values of a variable depends on the other variable, then it called dependent variable.
If the value of a variable does not depend on the other, then it is called independent variable.
If a function is f(x)=x, then x is an independent variable and f(x) is a dependent variable.
The given function is

Here, x is the input, or independent variable and f(x) is the output, or dependent variable or quantity.
The notation f(a) represents the output (y-value) when x = a. So, f(2) represents the output (y-value) when x = 2.
Substitute x=2 in the given function.



The value of f(2) is 2.