copyright © 2011 pearson education, inc. publishing as prentice hall. 2.5 dividing fractions and...
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Copyright © 2011 Pearson Education, Inc. Publishing as Prentice Hall.
2.5
Dividing Fractions and Mixed Numbers
Martin-Gay, Basic Mathematics, 4e 22
Copyright © 2011 Pearson Education, Inc. Publishing as Prentice Hall.
Finding Reciprocals of Fractions
Definition Example
Reciprocals: Two numbers are reciprocals of each other if their product is 1.
Reciprocal of a fraction: To find the reciprocal of a fraction, interchange its numerator and denominator.
9 101
10 9
1 11
11 1
p 152
Martin-Gay, Basic Mathematics, 4e 33
Copyright © 2011 Pearson Education, Inc. Publishing as Prentice Hall.
Examples
Find the reciprocal of each number. (Similar to Practice 1-4)
a.
b.
c.
d.
13
9
9
13
4
9
9
4
9
1
1
9
8
1 8
p 152
Martin-Gay, Basic Mathematics, 4e 44
Copyright © 2011 Pearson Education, Inc. Publishing as Prentice Hall.
Dividing Fractions
p 152
Martin-Gay, Basic Mathematics, 4e 55
Copyright © 2011 Pearson Education, Inc. Publishing as Prentice Hall.
Examples
Divide and simplify.
a.
b. 14 2
17 5
4 8
5 1
4 1
5 8
32
5
35
17
2or 6
5
14 5
17 2
7 2 5
17 2
12
17
p 152
Martin-Gay, Basic Mathematics, 4e 66
Copyright © 2011 Pearson Education, Inc. Publishing as Prentice Hall. P 153
What is dividing?How many 5s are there in 10?
Dividing Fractions
How many are there in s8
1?
4
3
2
6
2510
64
24
1
8
4
3
8
1
4
3
Martin-Gay, Basic Mathematics, 4e 77
Copyright © 2011 Pearson Education, Inc. Publishing as Prentice Hall.
Practice Problems
Divide and simplify.
5.
6.
7.
P 153
142
53
5
14
2
3
9
2
7
8
7
15or
7
36
2
1
9
4
33
222
9
8
28
15
2
9
7
8
27
924
14
5
2
3
1
2
9
4
Dividing Fractions
Martin-Gay, Basic Mathematics, 4e 88
Copyright © 2011 Pearson Education, Inc. Publishing as Prentice Hall.
Dividing Fractions and Mixed Numbers or Whole Numbers
Dividing Fractions and Mixed Numbers or Whole NumbersTo divide with a mixed number or a whole number, first write the mixed or whole number as a fraction and then divide as usual.
P 154
Martin-Gay, Basic Mathematics, 4e 99
Copyright © 2011 Pearson Education, Inc. Publishing as Prentice Hall.
Examples
Divide and simplify.
a.
b. 14 3
5
3 1
5 9
39
5
1
15
5 1or 1
4 4
3 1
5 3 3
36 16 36 5 2 2 3 3 5
9 5 9 16 3 3 2 2 2 2
Martin-Gay, Basic Mathematics, 4e 1010
Copyright © 2011 Pearson Education, Inc. Publishing as Prentice Hall.
Examples
Divide.
a.
b. 2
6 05
190 0
12
120
19
is undefined
Martin-Gay, Basic Mathematics, 4e 1111
Copyright © 2011 Pearson Education, Inc. Publishing as Prentice Hall.
Practice Problems
Divide and simplify.
8.
9.
10.
79
4
5
43
15
8
57
8
14
32
7
23
317
7223
31
151or
31
46
63
4
19
5
15
8
1953
58
7
1
9
4
31
14
7
23
Do Practice 11 and 12 on page 160.
Dividing Fractions and Mixed Numbers
Martin-Gay, Basic Mathematics, 4e 1212
Copyright © 2011 Pearson Education, Inc. Publishing as Prentice Hall.
Practice Problems
Divide and simplify.
11.
12.
017
14
8
120 0
undefined
Dividing Fractions and Mixed Numbers
Martin-Gay, Basic Mathematics, 4e 1313
Copyright © 2011 Pearson Education, Inc. Publishing as Prentice Hall.
Examples
If there are grams of fat in 4 ounces of lean hamburger meat, how many grams of fat are in an ounce?
3
113
113
3
40
3 4
1
40 1
3 4
5 2 2 2 1
3 2 2
10 1
or 33 3
There are grams of fat in 4 ounces.13
3
Martin-Gay, Basic Mathematics, 4e 1414
Copyright © 2011 Pearson Education, Inc. Publishing as Prentice Hall.
Practice Problem 13Practice Problem 13
SOLUTIONSOLUTION
A designer if women’s clothing designs a woman’s dress that requires 2 1/7 yards of material. How many dresses can be made from a 30-yard bolt of material?
7
1230
15
7215
dresses 14
Solving Problems by Dividing Fractions
15
7
1
30
Martin-Gay, Basic Mathematics, 4e 1515
Copyright © 2011 Pearson Education, Inc. Publishing as Prentice Hall.
DONE