Since rational expressions are just fractions with variables in the denominator, we are going to start by reviewing operations with fractions that do not contain variables. Then we will move on to performing the same operations on rational expressions.

Let’s start with multiplication. Remember that to multiply two fractions together, you simply multiply the numerators together and multiply the denominators together. You should also remember that if you can simplify each

fraction (cross-cancel) before multiplying, you should

When dividing fractions, you leave the first

fraction as it is, you find the reciprocal, or flip, the second

fraction and change the division problem to a multiplication problem.

Addition and subtraction of fractions involves having a common denominator. If the fractions already have the same denominator, you just add the numerators and keep the denominator the same. If the fractions do not have the same denominator, you have to find the least common denominator and create equivalent fractions before adding or subtracting.

Now let’s see how all of this relates to operations with rational functions.

**Multiplication**When working with multiplication problems, you should begin by factoring any terms that can be factored. For help with factoring,

click here. Once you have the problem in factored form, divide out any common factors and simplify the expression. If you need help with simplifying rational expressions,

click here.