Adding and Subtracting 5 2 with Unlike Denominators

$Adding and Subtracting 5 -2 with Unlike Denominators Learn to add and subtract fractions$

Adding and Subtracting 5 -2 with Unlike Denominators Learn to add and subtract fractions with unlike denominators.

Adding and Subtracting 5 -2 with Unlike Denominators Vocabulary least common denominator (LCD)

Adding and Subtracting 5 -2 with Unlike Denominators 1 3 The Pacific Ocean covers __ of Earth’s surface. The Atlantic 1 5 Ocean covers __ of Earth’s surface. To find the fraction of 1 __ Earth’s surface that is covered by both oceans, you can add 3 1 __ and , which are unlike fractions. 5

$Adding and Subtracting 5 -2 with Unlike Denominators To add or subtract unlike fractions,$

Adding and Subtracting 5 -2 with Unlike Denominators To add or subtract unlike fractions, first rewrite them as equivalent fractions with a common denominator. Remember! Fractions that represent the same value are equivalent.

Adding and Subtracting 5 -2 with Unlike Denominators Additional Example 1: Cooking Application 1 4 Mark made a pizza with pepperoni covering __ of the pizza and onions covering another 1 __. What fraction of 3 the pizza is covered by pepperoni and onions? 1 1 Add __ + __. 4 3 1 __ 4 1 __ + 3 _____ 1 __ 4 1 __ 3 ? Find a common denominator for 4 and 3: 4 x 3 = 12.

Adding and Subtracting 5 -2 with Unlike Denominators Additional Example 1 Continued 1 __ 4 3 __ 12 1 4 __ __ + 3 _____ 12 _______ 7 __ 12 Write equivalent fractions with 12 as the common denominator. Add the numerators. Keep the common denominator. 1 __ 4 1 12 1 __ 3 1 12 The pepperoni and onions cover 1 12 7 __ of the pizza. 12

Adding and Subtracting 5 -2 with Unlike Denominators Check It Out: Example 1 1 Tori made a pizza with peppers covering __ of the pizza 3 1 __ and ham covering another. What fraction of the pizza 2 is covered by ham and peppers? 1 1 Add __+ __. 3 2 1 __ 3 1 __ + 2 _____ 1 __ 3 1 __ 2 ? Find a common denominator for 3 and 2: 3 X 2 = 6.

Adding and Subtracting 5 -2 with Unlike Denominators Check It Out: Example 1 Continued 2 __ 6 Write equivalent fractions with 6 as the common denominator. 1 3 __ __ + 2 _____ 6 _______ Add the numerators. Keep the common denominator. 1 __ 3 5 __ 6 1 __ 3 1 6 1 __ 2 1 6 1 6 5 The peppers and ham cover __ of the pizza. 6

Adding and Subtracting 5 -2 with Unlike Denominators You can use any common denominator or the least common denominator to add and subtract unlike fractions. The least common denominator (LCD) is the least common multiple of the denominators.

Adding and Subtracting 5 -2 with Unlike Denominators Additional Example 2 A: Adding and Subtracting Unlike Fractions Add or subtract. Write each answer in simplest form. Method 1: Multiplying denominators. 7 3 __ __ – 10 8 7 3 __ – __ 10 8 Multiply the denominators. 10 • 8 = 80 56 30 __ – __ 80 80 Write equivalent fractions with a common denominator. 26 __ 80 Subtract. 13 __ 40 Write the answer in simplest form.

Adding and Subtracting 5 -2 with Unlike Denominators Additional Example 2 B: Adding and Subtracting Unlike Fractions Add or subtract. Write each answer in simplest form. Method 2: Use the LCD. 11 3 __ __ – 12 8 22 9 __ __ – 24 24 13 __ 24 Multiples of 12: 12, 24, … Multiples of 8: 8, 16, 24, … The LCD is 24. Write equivalent fractions with a common denominator. Subtract.

Adding and Subtracting 5 -2 with Unlike Denominators Additional Example 2 C: Adding and Subtracting Unlike Fractions Add or subtract. Write each answer in simplest form. Method 3: Use mental math. 5 1 __ __ + 16 8 5 1 __ + __ 16 8 Think: 16 is a multiple of 8, so the LCD is 16. 5 2 __ __ + 16 16 1 Rewrite __ with a denominator of 16. 7 __ 16 8 Add.

Adding and Subtracting 5 -2 with Unlike Denominators Additional Example 2 D: Adding and Subtracting Unlike Fractions Add or subtract. Write each answer in simplest form. Method 3: Use mental math. 5 1 __ __ – 16 8 5 1 __ – __ 16 8 Think: 16 is a multiple of 8, so the LCD is 16. 5 2 __ __ – 16 16 1 __ Rewrite with a denominator of 16. 8 3 __ 16 Subtract.

Adding and Subtracting 5 -2 with Unlike Denominators Check It Out: Example 2 A Add or subtract. Write each answer in simplest form. Method 1: Multiplying denominators. 8 2 __ – __ 10 6 Multiply the denominators. 10 • 6 = 60 48 20 __ – __ 60 60 Write equivalent fractions with a common denominator. Subtract. 28 __ 60 7 __ 15 Write the answer in simplest form.

Adding and Subtracting 5 -2 with Unlike Denominators Check It Out: Example 2 B Add or subtract. Write each answer in simplest form. Method 2: Use the LCD. 1 4 __ – __ 3 7 4 1 __ – __ 7 3 12 7 __ – __ 21 21 5 __ 21 Multiples of 7: 7, 14, 21, … Multiples of 3: 3, 6, 9, 12, 15, 18, 21, … The LCD is 21. Write equivalent fractions. Subtract.

Adding and Subtracting 5 -2 with Unlike Denominators Check It Out: Example 2 C Add or subtract. Write each answer in simplest form. Method 3: Use mental math. 3 1 __ + __ 12 6 Think: 12 is a multiple of 6, so the LCD is 12. 3 2 __ __ + 12 12 1 Rewrite __ with a denominator of 12. 5 __ 12 6 Add.

Adding and Subtracting 5 -2 with Unlike Denominators Check It Out: Example 2 D Add or subtract. Write each answer in simplest form. Method 3: Use mental math. 3 1 __ __ – 12 6 Think: 12 is a multiple of 6, so the LCD is 12. 3 2 __ __ – 12 12 1 Rewrite __ with a denominator of 12. 1 __ 12 6 Subtract.