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

Course Multiplying Fractions 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? __

Course Multiplying Fractions 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

Course Multiplying Fractions Learn to multiply fractions.

Course Multiplying Fractions 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? 1 3 __ = 1 12 __ One way to find of is to make a model. Find of.

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

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

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

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

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

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

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

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

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

Course Multiplying Fractions Additional Example 2B: Evaluating Fraction Expressions b = 3 8 __ b _____ __ Substitute for b. 3 8 __ Use the GCF to simplify. The answer is in simplest form __ 3 8 Multiply.

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

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

Course Multiplying Fractions Check It Out: Example 2B c = 2 7 __ c _____ __ Substitute for c. 2 7 __ Use the GCF to simplify. The answer is in simplest form __ 2 7 Multiply.

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

Course Multiplying Fractions Lesson Quiz Multiply. Write each answer in simplest form 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? 3 5 __ __ 3 10 __ 1 8 __ __ 3 14 __ 1 10 __ 1 64 __ 1 10 __