University of Saskatchewan (Canada)
University of Saskatchewan: Partial Fraction Decompositions
A short lesson on rational expressions. Includes a definition, examples, and exercises to choose from from introductory, moderate, or advanced.
Texas A&M University
Wtamu Virtual Math Lab: College Algebra: Adding & Sub. Rational Expressions
Rational expressions have never been so easy! Use this site to learn how to add and subtract them with ease and confidence. And common denominators? No Problem! Great practice problems are included to see how much you've learned.
Purple Math
Purplemath: Adding & Subtracting Rational Expressions: Introduction
Finding common denominators is no problem with Purplemath. Use this lesson to learn how to add and subtract rational expressions with these great examples.
Interactive Mathematics
Interactive Mathematics: Addition & Subtraction of Fractions
The addition and subtraction of algebraic expressions is presented with detailed examples and exercises for extra practice.