10.4 Multiplying

1
10.4 Multiplying Dividing Rational Expressions

• ALG. 13.0

2
Review

• Why are some values excluded?
• How do you find excluded values?
• How can a simplified rational expression have an
  excluded value when its denominator has no
  variables?
• How is simplifying a rational expression similar
  to simplifying a fraction? How is it different?
• How is -1 used to simplify opposite binomials?

3
Main Idea

• Today we are going to multiply and divide
  rational expressions.
• Use the same strategies as multiplying and
  dividing fractions.
• Use factor methods from chapter 8.
• Use methods from 10.3 for simplifying.

4
Multiplication

• Just like multiplying fractions, you can
• Multiply numerators, then multiply denominators
• Cross cancel

5
Ex.1 Multiply Rational Expressions
6
Practice
7
Ex.2 Multiply by a Polynomial

• Just like multiplying a fraction by a whole
  number, put a 1 in the denominator.

8
Practice
9
Ex.3 Rational Expression with Polynomials

• Method 1 simplify first, then multiply.
• Method 2 multiply first, then simplify.

10
Practice
11
Division

• Just like dividing fractions
• Flip the second rational expression, then
  multiply. (multiply by the reciprocal)

12
Ex.4 Dividing
13
Practice
14
Review

• How do you find common factors?
• What does it mean to divide out common factors?
• Which method do you prefer for multiplying? Why?
• Why do you multiply by the reciprocal instead of
  dividing?