### Learning Outcomes

By the end of this section, you will be able to:

- Identify polynomial expressions
- Evaluate polynomial expressions
- Find the greatest common factor of a list of expressions
- Find the greatest common factor of a polynomial
- Recognize and define a rational expression
- Determine the domain of a rational expression
- Simplify a rational expression

Before we can perform algebraic operations on polynomials and rational expressions, we need to be able to recognize and define these objects. We’ll also need to review some skills that make our work on these expressions possible.

We’ve already seen how finding the least common multiple makes it possible to do addition and subtraction on fractions. The greatest common factor is another object we can find that makes it possible to work with polynomial expressions in useful ways. Finally, we’ll extend our knowledge of fractions as ratios of expressions by defining and simplifying rational expressions.

Warm up for this module by refreshing these important concepts and skills. As you study these review topics, recall that you can also return to Module 1 Algebra Essentials any time you need to refresh the basics.

### Recall for success

Look for red boxes like this one throughout the text. They’ll show up just in time to give helpful reminders of the math you’ll need, right where you’ll need it.