Calculus is the mathematical study of change, and real-life things that change
are modeled by functions. Precalculus is essentially the study of
functions, with a few other related topics that supplement the study of
functions and prepare students for calculus. In this text we'll concern
ourselves first with learning about general functions, and later with certain
types of common functions with special properties, like
polynomial,
exponential,
logarithmic, and
trigonometric functions. First,
it is of critical importance to understand exactly what a function is. In the
following lessons, we'll discuss what makes a function a function, some general
properties of functions, and a few basic categories of functions. In this text
we'll assume a general knowledge of algebraic principles of solving equations,
working with the real numbers, and working with sets. In the last of the
upcoming sections, we'll learn how functions behave under operations like
addition, subtraction, etc.