CHAPTER8 Variables and Expressions
In This Chapter
- Writing expressions with
variables - Finding values for
variables - Multiplying with the help
of exponents - Dividing with variables
One of the markers of the shift from arithmetic to algebra
is the introduction of variables. In arithmetic, you know the
numbers and you know what operations need to happen. In
algebra, you step into the world of the unknown. You know
some, but not all, of the numbers, and you know the result of
the operations. A lot of your work is going backward to try
to fill in the unknown pieces. Until you figure out what they
are, those unknown numbers are represented by variables.
In this chapter, you’ll learn what variables are and how
to write phrases and sentences that use them. When you
start using variables, it’s important to consider what kind of
number the variable might be standing in for. Those numbers
are called the domain of the variable. This is also a time to
look at some of the arithmetic you can do with variables and
learn where you need to be especially careful and why.