# Rational Expressions 1 - Introduction

Taught by YourMathGal
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Lesson Summary:

In this lesson, we are introduced to rational expressions and learn that they are fractions, and that they become undefined when the denominator equals 0. By plugging in values for x, we can simplify rational expressions and determine when they are undefined. Additionally, we learn that any number divided by 0 is undefined, and that 0 divided by 0 is also undefined.

Lesson Description:

This is an introduction to Rational Expressions in beginning algebra.

More free YouTube videos by Julie Harland are organized at http://yourmathgal.com

• What are rational expressions?
• How do you find the value of a rational expression when you know the value of x?
• What is the value of (x + 9)/(x - 2) when x = -3?
• What does (x^2 + 1)/(2x) equal when x = -3?
• What is the value of (2x + 11)/(x + 3) when x = -3?
• What does 5/0 equal?
• How do you know which numbers make a rational expression undefined?
• When is 5/(x - 2) undefined?
• For what values of x is (x + 5)/3x undefined?
• When is (x^2 + 1)/7 undefined?
• When is (x + 5)/(x^2 - 16) undefined?
• Why is a fraction undefined if 0 is in the denominator?
• Why can you not divide by 0?
• What does 8/0 mean?
• Why is it undefined when you divide a number by 0?
• What does 0/0 equal?
• Why is 0/0 undefined?
• #### Staff Review

• Currently 4.0/5 Stars.
This lesson shows some good examples of substituting a numerical value into some expressions to find what they equal. You also learn how to determine what values of x make a rational expression undefined. Some great examples really drive home the concepts in this lesson.