5-1 Multiplying Fractions
Today I will multiply fractions.
Course 1
5-1 Multiplying Fractions
Additional Example 1A: Multiplying Fractions
Multiply. Write the answer in simplest form.
1
2
__
__
•
A.
4
5
1
2
1•2
__
__
= _____
•
4•5
4
5
=
2
__
20
1
__
=
10
Course 1
Multiply numerators. Multiply
denominators.
The GCF of 2 and 20 is 2.
The answer is in simplest form.
5-1 Multiplying Fractions
Additional Example 1B: Multiplying Fractions
Multiply. Write the answer in simplest form.
5
4
__
__
•
B.
7 15
1
5
4
1
4
__
__
__
__
=
•
•
7
15
7
3
3
1•4
_____
=
7•3
4
__
=
Course 1
21
Use the GCF to simplify the fractions
before multiplying. The greatest
common factor of 5 and 15 is 5.
Multiply numerators. Multiply
denominators.
The answer is in simplest form.
5-1 Multiplying Fractions
Additional Example 1C: Multiplying Fractions
Multiply. Write the answer in simplest form.
4
6
__
__
•
C.
9 10
4
6
4•6
__
__
= ______
•
9 • 10
9
10
=
24
__
90
4
__
=
15
Course 1
Multiply numerators. Multiply
denominators.
The GCF of 24 and 90 is 6.
The answer is in simplest form.
5-1 Multiplying Fractions
Try This: Example 1A
Multiply. Write the answer in simplest form.
1
3
__
__
•
A.
2
6
1
3
1•3
__
__
= _____
•
2•6
2
6
Course 1
Multiply numerators. Multiply
denominators.
=
3
__
12
The GCF of 3 and 12 is 3.
=
1
__
4
The answer is in simplest form.
5-1 Multiplying Fractions
Try This: Example 1B
Multiply. Write the answer in simplest form.
3
5
__
__
•
B.
7
9
1
3
5
1
5
__
__
__
__
=
•
•
7
9
7
3
3
1•5
_____
=
7•3
5
__
=
Course 1
21
Use the GCF to simplify the fractions
before multiplying. The greatest
common factor of 3 and 9 is 3.
Multiply numerators. Multiply
denominators.
The answer is in simplest form.
5-1 Multiplying Fractions
Try This: Example 1C
Multiply. Write the answer in simplest form.
3
5
__
__
•
C.
7 15
3
5
3•5
__
__
= ______
•
7
15
7 • 15
=
15
____
105
1
__
=
7
Course 1
Multiply numerators. Multiply
denominators.
The GCF of 15 and 105 is 15.
The answer is in simplest form.
5-1 Multiplying Fractions
Additional Example 2A: Evaluating Fraction
Expressions
2
Evaluate the expression b • __ for each value of b.
5
Write the answer in simplest form.
A. b =
1
__
3
2
b • __
5
1 __
2
__
•
3 5
1•2
_____
3•5
2
__
15
Course 1
Substitute
1
__
for b.
3
Multiply.
The answer is in simplest form.
5-1 Multiplying Fractions
Try This: Example 2A
1
__
for each value of c.
4
Write the answer in simplest form.
Evaluate the expression c
1
__
A. c =
7
1
c • __
4
1 __
1
__
•
7 4
1•1
_____
7•4
1
__
28
Course 1
•
1
__
Substitute
for c.
7
Multiply.
The answer is in simplest form.
5-1 Multiplying
Insert Lesson
Fractions
Title Here
Lesson Quiz
Multiply. Write each answer in simplest form.
1
1. __
3
__
•
4
5
3
__
20
3
2. __
10
5
• __
3
__
14
7
1 for each value of
Evaluate the expression x • __
8
x. Write the answer in simplest form.
1
1
__
__
4. x =
8
64
2
5. At a particular college __ of the students take a
5
1
__
4
__
3. x =
5
1
__
10
math class. Of these students
take basic algebra.
4
1
What fraction of all students take basic algebra? __
10
Course 1
4-9 Multiplying Fractions by Whole Numbers
Lesson Quiz
Multiply. Write each answer in simplest form.
2
1 __
3
1. 10 • __
2. 6 • __
4
5
10 5
Evaluate 6x for each value of x. Write your answer
in simplest form.
1 __
3
1
__
3. x = __
, or 1
4 2
2
5
4. x = __
6
5
5. Alicia spent 30 minutes making a pizza. Of those
1 were spent rolling out the crust. How many
minutes __
5
minutes did Alicia spend rolling out the crust?
6 minutes
Course 1