1. Copyright © 2012 Pearson Education, Inc. Publishing as Prentice Hall. Chapter 3 Fractions

2. Copyright © 2012 Pearson Education, Inc. Publishing as Prentice Hall. 3.4 Adding and Subtracting Like Fractions, Least Common Denominator, and Equivalent Fractions

3. 33 Copyright © 2012 Pearson Education, Inc. Publishing as Prentice Hall. Adding Like Fractions Fractions with the same denominator are called like fractions. Fractions that have different denominators are called unlike fractions.

4. 44 Copyright © 2012 Pearson Education, Inc. Publishing as Prentice Hall. Adding or Subtracting Like Fractions Adding or Subtracting Like Fractions (Fractions with the Same Denominator) If a, b, and c represent nonzero whole numbers, we have

5. 55 Copyright © 2012 Pearson Education, Inc. Publishing as Prentice Hall. Examples Add and simplify. a. b.

6. 66 Copyright © 2012 Pearson Education, Inc. Publishing as Prentice Hall. Examples Subtract and simplify. a. b.

7. 77 Copyright © 2012 Pearson Education, Inc. Publishing as Prentice Hall. Examples Add or Subtract. a. b.

8. 88 Copyright © 2012 Pearson Education, Inc. Publishing as Prentice Hall. Solving Problems by Adding or Subtracting Like Fractions Find the perimeter of the following rectangle. Rectangle Perimeter

9. 99 Copyright © 2012 Pearson Education, Inc. Publishing as Prentice Hall. Example A recipe calls for 1/3 of a cup of brown sugar and 2/3 of a cup of white sugar. How much total sugar is in the recipe? Total sugar = brown sugar + white sugar The total amount of sugar needed in the recipe is 1 cup.

10. 10 Copyright © 2012 Pearson Education, Inc. Publishing as Prentice Hall. Finding the Least Common Multiple Using Multiples Method 1: Find the LCM of a List of Numbers Using Multiples of the Largest Number Step 1: Write the multiples of the largest number (starting with the number itself) until a multiple common to all numbers in the list is found. Step 2: The multiple found in Step 1 is the LCM.

11. 11 Copyright © 2012 Pearson Education, Inc. Publishing as Prentice Hall. Example Find the LCM of 9 and 12. Write the multiples of 12 until we find a number that is also a multiple of 9. 12  1 = 12 Not a multiple of 9. 12  2 = 24 Not a multiple of 9. 12  3 = 36 A multiple of 9. The LCM of 9 and 12 is 36.

12. 12 Copyright © 2012 Pearson Education, Inc. Publishing as Prentice Hall. Finding the Least Common Multiple Using Multiples Method 2: Find the LCM of a List of Numbers Using Prime Factorization Step 1: Write the prime factorization of each number. Step 2: For each different prime factor in step 1, circle the greatest number of times that factor occurs in any one factorization. Step 3: The LCM is the product of the circle factors.

13. 13 Copyright © 2012 Pearson Education, Inc. Publishing as Prentice Hall. Example Find the LCM of 72 and 60. Circle the greatest number of prime factors found in either factorization. The LCM is the product of the circle factors.

14. 14 Copyright © 2012 Pearson Education, Inc. Publishing as Prentice Hall. Example Find the LCM of 15, 18, and 54.

15. 15 Copyright © 2012 Pearson Education, Inc. Publishing as Prentice Hall. Writing Equivalent Fractions To add or subtract unlike fractions, we first write equivalent fractions with the LCM as the denominator. To write an equivalent fraction, where a, b, and c are nonzero numbers.

16. 16 Copyright © 2012 Pearson Education, Inc. Publishing as Prentice Hall. Example Write an equivalent fraction with the indicated denominator.

17. 17 Copyright © 2012 Pearson Education, Inc. Publishing as Prentice Hall. Example Write an equivalent fraction with the indicated denominator.