Precalculus is important preparation for calculus; it also draws on algebra, trigonometry and other topics; the essential concept of the function; trying hand at simple problems; Professor Edwards's recommendations for approaching the series.

The world of complex numbers, where i is defined as the square root of -1; learning how to calculate and find roots of polynomials using complex numbers; how certain complex expressions produce beautiful fractal patterns when graphed.

Functions can be combined in ways including addition, multiplication and composition; the inverse function has important applications; recognizing inverse functions on a graph; the function and its inverse form mirror images across the line y = x.

Using inequalities to express the set of values in the domain of a function; the notation for inequalities; how to represent inequalities on graphs; techniques to solve inequalities; those involving absolute value, which occur frequently in calculus.