Lesson 2-6

Example 1 Add Unlike Fractions
Find . Write in simplest form.

			The LCD is 2 ∙ 2 ∙ 2 or 8.
	     = 			Rename the fractions using the LCD.
	     = 				Add the numerators.
	     = 				Simplify.

Example 2 Subtract Unlike Fractions
Find . Write in simplest form.

		The LCD is 2 ∙ 2 ∙ 3 or 12.
	        = 			Rename each fraction using the LCD.
	        = 			Subtract  by adding its inverse, .
	        = 				Add the numerators.
	        = 				Simplify.

Example 3 Add Mixed Numbers
Find . Write in simplest form.

		Write the mixed numbers as fractions.
	      = 		The LCD is 2 ∙ 2 ∙ 2 ∙ 3 or 24.
	      = 		Rename each fraction using the LCD.
	      = 		Add the numerators.
	      = 		Simplify.

Example 4 Standardized Test Practice Example
Three books are  inches thick. If these books were stacked one on top of another, what is the total height of the books?
A   in.		C   in.
B   in.		D   in.

Read the Test Item  You need to find the sum of three mixed numbers.

Solve the Test Item  It would take some time to change each of the fractions to ones with a common denominator. However, notice that all three of the numbers are about 2. Since 2  3 = 6, the answer will be about 6. Notice that only one of the choices is close to 6. The answer is A.