# Finding the LCD of rational expressions

Taught by YourMathGal
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Lesson Summary:

In this lesson, you will learn how to find the least common denominator (LCD) of rational expressions. The LCD is the least common multiple of the denominators, factored in the case of algebraic fractions. You can use a building-up approach or find the least common multiple of the numerical parts and each kind of factor. Factoring the denominators is the first step in finding the LCD, and then you can build it up by multiplying the missing factors. It is important to leave the LCD in factor form for ease of adding fractions.

Lesson Description:

This video shows a method for finding the least common denominator of rational expressions. I've posted at least 2 other videos with methods, explanations, and examples for finding the LCD.

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

• What is the least common denominator or LCD?
• How do you find the least common denominator of algebraic fractions?
• What is the least common denominator of 3/2x^2 and 5/6xy?
• How do you find the LCD of algebraic fractions if the denominators are not factored?
• How do you find the LCD of x/(9x + 9) and (x + 4)/6x?
• What is the LCD of (3x + 5)/(x - 7) and 4/(x + 5)?
• What is the least common denominator of 5/(7x - 14) and 3x/(x^2 - 4)?
• How do you find the least common denominator of 3 algebraic fractions?
• What is the LCD of 4/(3x + 15), 1/(4x - 20), and 1/(x^3 - 25x)?
• #### Staff Review

• Currently 4.0/5 Stars.
This lesson shows how to find least common denominators when there are variables involved. The methods shown for finding the least common denominator are the same as with just numbers; you will just have to deal with algebraic expressions now. Several examples are shown and explained in this video.