Download Topic 4 - Multip & Divide Rational Expr

Multiplying and Dividing
Rational Expressions
Multiplying Rational Expressions
Multiplying rational expressions when P, Q, R, and
S are polynomials with Q  0 and S  0.
P R PR
 
Q S QS
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Multiplying Rational Expressions
Multiplying rational expressions
1) Factor the numerators and denominators.
2) Multiply the numerators and
multiply the denominators.
3) Simplify
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Multiplying Rational Expressions
Example
Multiply the following
3 6 3 3 2 33 2

  
7 9 7 33 7 33
2
7
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Multiplying Rational Expressions
Example
Multiply the following rational expressions.
2 3 x  x 5 x
6 x 5x
1



3
10 x 12 2  5  x  x  x  2  2  3
4
2
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Multiplying Rational Expressions
Example
Multiply the following rational expressions.
( m  n)
m
(m  n)( m  n)  m
 2


m  n m  mn (m  n)  m(m  n)
2
mn
mn
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How do I
divide
fractions? 1. Copy the first fraction
2. Change the division sign to
multiplication
3. Flop (flip) the second fraction
4. Multiply
5. Write your answer in simplest form
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Dividing Rational Expressions
Example
Divide the following rational expression.
25
( x  3) 5 x  15 ( x  3)




5
5 x  15
5
25
2
2
( x  3)( x  3)  5  5
 x3
5  5( x  3)
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Dividing Rational Expressions
7x
x  6x
 2
2x  10 x  11x  30
2

2 2
7x
x x 11x
 6x 30
 2 2
2x  10 x x11x 6x30
7x
x  5x  6 7



2x  5
xx  6
2



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
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Example of Dividing
Rational Expressions
2y 8y  4y


9
27
2
5
3
2
2y
27
 5

3
9 8y  4y
3
2
2y
27
 3 2

9 4 y 2 y  1
1
2 y
3
2
2 y 2 y 1
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

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Example of Dividing
Rational Expressions
So, I’m a bit confused on a few
questions. I hope you can help me
out. I need your expertise on
solving these brain-twister.
Martin-Gay, Developmental Mathematics
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