Carson Elementary And Intermediate Algebra 3e
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4M098
Carson Elementary and Intermediate Algebra 3e
Section 7.2
Objectives
1.
Multiply rational expressions.
2.
Divide rational expressions
3.
Convert units of measurement using dimensional analysis.
Vocabulary
Prior Knowledge
Multiplication and Division of fractions
New Concepts
1. Multiply rational expressions.
Again, remember back to when you learned to multiply fractions.
8
3
9
4
When you first learned to do these, you probably learned to multiply the numerators together, multiply
the denominators and then reduce your answer.
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3
24
2
9
4
36
3
Later, you learned that you could actually reduce before you multiplied by removing common factors in
the numerator and denominator.
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2
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As long as the factor is the same in the numerator and the denominator, it can be reduced to 1. This
only works because they are factors.
The same process works when we multiply rational expressions. The common factors in the numerator
and denominator reduce to 1.
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c
c 2
c
4
c
4
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2
c
4
c
c
2
’s or the 4’s reduce? No - they are terms not factors!!!!
Will the c
Factor all the numerators and denominators and then reduce.
c
c
2
c
2
c
2
c
2
c
2
c
c
1
When the numerator and denominator contain the same factor, it is the same as dividing a number by
itself. It always equals one.
c
c
2
c
2
c
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c
c
1
c
1
V. Zabrocki 2011
page 1
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