Maple is a "C.A.S", i.e., a C omputer A lgebra S ystem. This means that Maple knows every rule of algebra that you know. As you progress through calculus, differential equations and linear algebra you will find that Maple also has the essential operations from those subjects built into its large command set. In this section you will learn how to enter an algebraic expression and substitute values in for the variables. Then you will learn the commands that allow you to expand, factor and simplify expressions.