What is function notation?

Function notation is a way to represent a function in a clear and specific format that emphasizes the relationship between the input and the output. The notation f(x) indicates that the function named f takes an input x and produces an output f(x). This representation helps to distinguish the function from a simple variable, allowing for a better understanding of its behavior and properties.

Using f(x) is particularly useful when dealing with multiple functions or when a function is defined by an equation, as it conveys that the output is dependent on the input value. This form also allows for easier manipulation of functions, such as function composition or evaluation at specific points, enhancing clarity in mathematical communication.

The other options represent equations or specific forms of expressions but do not illustrate the concept of function notation as effectively as f(x) does.