4-8 dividing fractions and mixed numbers course 2 warm up warm up problem of the day problem of the...
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4-8 Dividing Fractions and Mixed Numbers
Course 2
Warm UpWarm Up
Problem of the DayProblem of the Day
Lesson PresentationLesson Presentation
Warm UpMultiply.
Course 2
4-8 Dividing Fractions and Mixed Numbers
1. 7 9· 3
6
2. 98· 65
3. 15
2 ·7
4. 212· 14
7182720
720
or 1
2775 5
or 15
258 8
or 3 1
Problem of the Day
The Jeffers family is putting in a new fence around their yard. The yard is in the shape of a square. If they put nine fence posts on each side of the square, how many posts will be used?32
Course 2
4-8 Dividing Fractions and Mixed Numbers
Learn to divide fractions and mixed numbers.
Course 2
4-8 Dividing Fractions and Mixed Numbers
Vocabulary
reciprocal
Insert Lesson Title Here
Course 2
4-8 Dividing Fractions and Mixed Numbers
Course 2
4-8 Dividing Fractions and Mixed Numbers
When you divide 8 by 4 you find how many 4’s there are in 8. Similarly, when you divide
2 by , you find how many ’s there are in 2. 13
13
There are six ’s in 2. 13
Course 2
4-8 Dividing Fractions and Mixed Numbers
Reciprocals can help you divide by fractions. Two numbers are reciprocals if their product
is 1. The reciprocal of is 3 because 13
13
· 3= 13
· 31
= 33
= 1.
To divide by a fraction, find its reciprocal and thenmultiply.
2 ÷ 13
= 2 · 3 = 6
Additional Example 1A & 1B: Dividing Fractions
Divide. Write each answer in simplest form.
A. 37 ÷ 2
537
÷ 25
= 37 ·
52
= 37
· 5· 2
=1514
or 1141
Multiply by the reciprocal of . 25
B. 38
÷ 12
38
÷ 12 =38
· 112
=38
· 112
1
4=
Multiply by the reciprocal of 12.
132
Course 2
4-8 Dividing Fractions and Mixed Numbers
Simplify.
Try This: Example 1A & 1B
Divide. Write each answer in simplest form.
A. 35 ÷ 1
235
÷ 12
= 35 ·
21
= 35
· 2· 1
=65
or 151
Multiply by the reciprocal of . 12
B. 34
÷ 3
34
÷ 3 =34
· 13
=34
· 13
1
1=
Multiply by the reciprocal of 3.
14
Course 2
4-8 Dividing Fractions and Mixed Numbers
Simplify.
Divide. Write each answer in simplest form.
Insert Lesson Title Here
Course 2
4-8 Dividing Fractions and Mixed Numbers
A. 523
÷ 1 14
5 23
÷ 114
= 17 3
÷ 54
= 17 3
· 45
= 6815
or 4 815
Write mixed numbers as improperfractions.
Multiply by the reciprocal of 54
B. 34
÷ 212
34
÷ 2 12
= 34
÷ 52
= 34
· 25
=3 · 24 · 5
1
2= 3
10
Write 2 as an improper fraction.12
Multiply by the reciprocal of . 52
Simplify.
.
Additional Example 2A & 2B: Dividing Mixed Numbers
Divide. Write the answer in simplest form.
Additional Example 2C: Dividing Mixed Numbers
Course 2
4-8 Dividing Fractions and Mixed Numbers
C. 823
÷ 1327
8 23
÷ 1327
= 26 3
÷ 1327
= 26 3
· 2713
9
1
2
1
= 18 1
or 18
Write 8 as an improper fraction.23
Multiply by the reciprocal of . 1327
=26 3
· 2713·
Divide. Write each answer in simplest form.
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Course 2
4-8 Dividing Fractions and Mixed Numbers
A. 3 23
÷ 1 12
3 23
÷ 112
= 11 3
÷ 32
= 11 3
· 23
= 22 9
or 2 4 9
Write mixed numbers as improperfractions.
Multiply by the reciprocal of 32
B. 35
÷ 125
35
÷ 1 25
= 35
÷ 75
= 35
· 57
=3 · 55 · 7
1
1= 3
7
Write 1 as an improper fraction.25
Multiply by the reciprocal of . 75
Simplify.
.
Try This: Example 2A & 2B
Divide. Write the answer in simplest form.
Try This: Example 2C
Course 2
4-8 Dividing Fractions and Mixed Numbers
C. 715
÷ 18 5
7 15
÷ 18 5
= 36 5
÷ 18 5
= 36 5
· 5_18
1
1
2
1
= 21
or 2
Write 7 as an improper fraction.15
Multiply by the reciprocal of . 18 5
= 36 5
· 518·
Additional Example 3: Social Studies Application
Course 2
4-8 Dividing Fractions and Mixed Numbers
The life span of a golden dollar coin is 30 years, while
paper currency lasts an average of 1 years. How many12
times longer will the golden dollar stay in circulation?
30 ÷ 1 12
= 30 1
÷ 32
Write the number as an improper fraction.
=30 1
· 23
Multiply by the reciprocal of .32
= ·Simplify.
30 21 3
10
1= 20
1or 20
The golden dollar will stay in circulation about20 times longer than paper currency.
·
Try This: Example 3
Course 2
4-8 Dividing Fractions and Mixed Numbers
The average life of a queen ant is approximately 3 years.The life span of a worker ant is year. How many 3
7times longer will the queen ant live?
3 ÷ 37
= 31
÷ 37
Write the number as an improper fraction.
=31
· 73
Multiply by the reciprocal of .37
= · Simplify.3 71 3
1
1= 7
1or 7
The queen ant will live 7 times longer than the worker ant.
·
Lesson Quiz
10
Insert Lesson Title Here
Course 2
4-8 Dividing Fractions and Mixed Numbers
Divide. Write each answer in simplest form.
1.
2.
8 ÷ 45
59
÷ 18
3. 35
÷ 6
4. 212
÷
5. There are 5 14
yards of silk in a roll. If it takes 34
of a yard to make one designer scarf, how many scarves can be made from the roll?
7
4 49
40 9
or
110
317
3544