The notation "f(b)" represents the value of a function f when the input is b. In mathematics, a function is a relationship that assigns each input exactly one output. For example, if f is defined as f(x) = x + 2, then f(3) would equal 5, since 3 + 2 = 5. In this context, b is often referred to as the argument or input of the function. The function f can take various forms, such as linear, quadratic, or exponential, depending on how it is defined. Understanding f(b) is essential for analyzing and solving mathematical problems involving functions.