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5-7

5-7. Multiplying Fractions. Course 1. Warm Up. Problem of the Day. Lesson Presentation. 1. 1. 1. 1. 1. __. __. __. __. __. 4. 2. 4. 2. 2. Warm Up 1. What is of 12? 2. What is of 100? 3. What is of 120? 4. What is of 100? 5. What is of 480?. 6. 50. 60.

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5-7

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  1. 5-7 Multiplying Fractions Course 1 Warm Up Problem of the Day Lesson Presentation

  2. 1 1 1 1 1 __ __ __ __ __ 4 2 4 2 2 Warm Up 1.What is of 12? 2. What is of 100? 3. What is of 120? 4. What is of 100? 5. What is of 480? 6 50 60 25 120

  3. Problem of the Day Your favorite uncle left one-fifth of his estate to each of his three children and the rest to his favorite charity. If his estate was worth $105,000, how much was given to charity? $42,000

  4. Learn to multiply fractions.

  5. 1 1 1 1 1 1 1 1 1 __ __ __ __ __ __ __ __ __ 3 4 4 3 4 3 3 12 4 On average, people spend of their lives asleep. About of the time they sleep, they dream. What fraction of a lifetime does a person typically spend dreaming? One way to find of is to make a model. Find of . = •

  6. 1 1 1 1 __ __ __ __ 12 12 4 3 You can also multiply fractions without making a model. 1 • 1 Multiply the numerators. _____ = • Multiply the denominators. 4 • 3 The answer is in simplest form. = A person typically spends of his or her lifetime dreaming.

  7. 1 1 2 2 1 2 __ __ __ __ __ __ 4 5 5 10 20 4 Additional Example 1A: Multiplying Fractions Multiply. Write each answer in simplest form. • 1 • 2 _____ Multiply numerators. Multiply denominators. = • 4 • 5 The GCF of 2 and 20 is 2. = The answer is in simplest form. =

  8. 5 1 4 4 4 5 4 __ __ __ __ __ __ __ 15 7 21 7 7 3 15 Additional Example 1B: Multiplying Fractions Multiply. Write each answer in simplest form. • Use the GCF to simplify the fractions before multiplying. The greatest common factor of 5 and 15 is 5. 1 = • • 3 1 • 4 _____ Multiply numerators. Multiply denominators. = 7 • 3 The answer is in simplest form. =

  9. 4 4 6 6 4 24 __ __ __ __ __ __ 9 10 10 15 90 9 Additional Example 1C: Multiplying Fractions Multiply. Write each answer in simplest form. • 4 • 6 ______ Multiply numerators. Multiply denominators. = • 9 • 10 The GCF of 24 and 90 is 6. = The answer is in simplest form. =

  10. 1 1 3 3 1 3 __ __ __ __ __ __ 2 6 6 4 12 2 Check It Out: Example 1A Multiply. Write each answer in simplest form. • 1 • 3 _____ Multiply numerators. Multiply denominators. = • 2 • 6 The GCF of 3 and 12 is 3. = The answer is in simplest form. =

  11. 3 1 5 5 5 3 5 __ __ __ __ __ __ __ 9 7 21 7 7 3 9 Check It Out: Example 1B Multiply. Write each answer in simplest form. • Use the GCF to simplify the fractions before multiplying. The greatest common factor of 3 and 9 is 3. 1 = • • 3 1 • 5 _____ Multiply numerators. Multiply denominators. = 7 • 3 The answer is in simplest form. =

  12. 3 5 1 5 3 __ __ __ __ __ 7 15 7 7 15 15 ____ 105 Check It Out: Example 1C Multiply. Write each answer in simplest form. • 3 • 5 ______ Multiply numerators. Multiply denominators. = • 7 • 15 The GCF of 15 and 105 is 15. = The answer is in simplest form. =

  13. 2 2 2 1 1 1 2 __ __ __ __ __ __ __ 5 3 5 5 3 15 3 _____ 1 • 2 3 • 5 Additional Example 2A: Evaluating Fraction Expressions Evaluate the expression b• for each value of b. Write each answer in simplest form. b• b = Substitute for b. • Multiply. The answer is in simplest form.

  14. Helpful Hint You can look for a common factor in a numerator and a denominator to determine whether you can simplify before multiplying.

  15. 3 3 3 3 2 2 3 2 __ __ __ __ __ __ __ __ 8 8 5 5 5 20 8 8 _____ 3 • 1 4 • 5 Additional Example 2B: Evaluating Fraction Expressions b = b• Substitute for b. • 1 Use the GCF to simplify. • 4 Multiply. The answer is in simplest form.

  16. 5 10 5 2 2 2 5 __ __ __ __ __ __ __ 7 35 7 7 5 5 7 _____ 5 • 2 7 • 5 Additional Example 2C: Evaluating Fraction Expressions b = b• Substitute for b. • Multiply. The GCF of 10 and 35 is 5. The answer is in simplest form.

  17. 1 1 1 1 1 1 1 __ __ __ __ __ __ __ 7 7 4 4 4 7 28 _____ 1 • 1 7 • 4 Check It Out: Example 2A Evaluate the expression c• for each value of c. Write each answer in simplest form. c = c• Substitute for c. • Multiply. The answer is in simplest form.

  18. 1 2 2 2 1 1 2 1 __ __ __ __ __ __ __ __ 7 7 4 4 4 14 7 7 _____ 1 • 1 7 • 2 Check It Out: Example 2B c = c• Substitute for c. • 1 Use the GCF to simplify. • 2 Multiply. The answer is in simplest form.

  19. 4 4 4 1 1 1 4 __ __ __ __ __ __ __ 7 28 7 7 4 4 7 _____ 4 • 1 7 • 4 Check It Out: Example 2C c = c• Substitute for c. • Multiply. The GCF of 4 and 28 is 4. The answer is in simplest form.

  20. 1 1 3 1 1 3 5 1 3 3 1 1 2 4 __ __ __ __ __ __ __ __ __ __ __ __ __ __ 20 8 5 5 8 4 10 7 14 10 4 64 5 10 Lesson Quiz Multiply. Write each answer in simplest form. 1.2. Evaluate the expression x• for each value of x. Write the answer in simplest form. 3.x = 4.x = 5. At a particular college of the students take a math class. Of these students, take basic algebra. What fraction of all students take basic algebra? • •

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