# Adding and Subtracting Rational Expressions

In this lesson I will teach you how to add and subtract rational expressions.  If you have been watching the lessons in this chapter in order you should know that we use the same steps in rational expressions as we do with fractions.  This topic is no different- we add and subtract rational expressions just like we add or subtract fractions.  Recall when we add/subtract fractions we need to determine if the fractions have the same LCD- if they do finding our answer is easy.  However if the fractions have different denominators we need to find the LCD and rewrite each fraction such that it’s denominator is the LCD.  We will be having to find the LCD of rational expressions so make sure you have mastered this skill (review the lesson in the chapter if need be).  Now if you can find the LCD and know the steps to add and subtract fractions you should be fine with this topic.  I can’t stress that what we are learning is pretty sophisticated so you absolutely need to practice to retain and master the skills.