# Chapter 7 - Vocabulary Check: 7

The $least$ $common$ $denominator$ of a list of rational expressions is a polynomial of least degree whose factors include all factors of the denominators in the list.

#### Work Step by Step

The $least$ $common$ $denominator$ is taken n when there are two or more fractions, and two or more have a different denominator. Thus, when we need to add or subtract them, we take the $least$ $common$ $denominator$ , which gives us a common denominator for all the fractions. Then , we can simply add or subtract all the numerators in the fractions, as the denominators are the same. Example: $\frac{3}{2}$ + $\frac{1}{3}$ = $\frac{3(3) + 2(1)}{3(2)}$ = $\frac{9 + 2}{6}$ = $\frac{11}{6}$

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