What is the function of 'f(x)' in mathematical terms?

In mathematical terms, 'f(x)' represents a function. A function is a specific type of relation that assigns each input exactly one output. In this notation, 'f' is the name of the function, while 'x' is the independent variable or input value. The function describes how to compute the output based on the input. For example, if you have a function defined as f(x) = x^2, then for every value of x that you input, the function will produce a corresponding output by squaring that input. This is the essence of what makes 'f(x)' a function, as it systematically defines a relationship between inputs (x values) and outputs (resulting f(x) values). Other options do not accurately encapsulate the idea of a function; a variable merely represents a quantity, an expression is a combination of numbers and variables without an equal sign, and a constant is a fixed value that does not change.