Transcript Section 2.4 Notes

Chapter 2
Fractions
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2.4
Multiplying Fractions
and Mixed Numbers
Copyright © 2012, 2009, 2005, 2002 Pearson Education, Inc.
Multiplying Fractions
Multiplication of fractions is used when we want to
take a fractional part of something.
1
5
5


2
9
18
5
9
1
2
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1
5
of
2
9
yields 5 out of
18 squares.
Multiplying Fractions
To multiply two fractions, we multiply the
numerators and multiply the denominators.
3
2
6


7
5
35
23  6
7  5  35
In general, for all positive whole numbers a, b, c, and d,
a
c
a  c


b
d
b  d
(when b and d are not 0).
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Multiplying Proper or Improper Fractions
12
3
Example: Multiply

.
17
24
12
3
12  3
36
3




17
24 17  24
408
34
Simplify the
fraction.
To make multiplying easier, the fractions may be simplified
before multiplying.
3
12
3  3  4 

17
2  3  4
17
24
1
1
3  4  3
3
3



17  2  3  4 17  2
34
1
1
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Multiplying Mixed Numbers
4
4
Example: Multiply 2
1 .
5
7
To multiply mixed numbers, first change each mixed
number into an improper fraction.
2
4
4
14
11
2 1


5
7
5
7
1
22
2

or 4
5
5
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