1. Multiplication and division of Real Numbers CHAPTER 1 Section 8
MTH Algebra
Multiplication and division of Real Numbers
CHAPTER 1 Section 8

2. Multiply Numbers The Sign of the Product of Two Real Numbers
Rule 1: The product of two numbers with like signs is a positive number
(-) · (-) = +
(+) · (+) = +
Rule 2: The product of two numbers with unlike signs is a negative number
(+) · (-) = -
(-) · (+) = -
Multiplication and division of decimals are covered in appendix A.

3. Multiply Numbers Example # 18: -4(2) = -8 neg. because different signs
Example # 21: (-8)(-10) = pos. because same signs
Example: (6)(-9) = -54 neg. because different signs

4. Multiply Numbers Example: (-8)(-4) = 32 pos. because same signs
Example: (0)(-8) = is never pos. or neg.
Example: (-4)(-6) = pos. because same signs
Careful not to confuse subtraction with multiplication
Example -4 – 5 (-4)(-5)
-4 + (-5) 20 -9

5. Multiply Numbers Example
Remember that negatives can be written different ways

6. Multiply Numbers
Multiplication of more that one number in a given problem:
Helpful hint:
Even number of negatives will equal a positive result
Odd number of negatives will equal a negative result
Example # 90 pg 67:
4(-2)(-1)(-5) Odd negatives equals negative results
(-8)(-1)(-5)
(8)(-5)
-40

7. Multiply Numbers Example :
(-3)(2)(-1)(-2)(-4) Even negatives equals (-6)(-1)(-2)(-4) positive results
(6)(-2)(-4)
(-12)(-4) 48
(-3)(4)(-9)(-3) Odd negatives equals (-12)(-9)(-3) Negative results
(108)(-3)
-324

8. Multiply Numbers Example :
(-2)(4)(-1)(-3)(-5) Even negatives equals (-8)(-1)(-3)(-5) positive results
(8)(-3)(-5)
(-24)(-5)
120

9. Divide Numbers The Sign of the Quotient of Two Real Numbers
Rule 1: The Quotient of two numbers with like signs is a positive number
(-) ÷ (-) = +
(+) ÷ (+) = +
Rule 2: The Quotient of two numbers with unlike signs is a negative number
(+) ÷ (-) = -
(-) ÷ (+) = -

10. Divide Numbers Example # 52 pg 66: Example # 50 pg 66: 25 ÷ 5 or

11. Divide Numbers
Example # 50 pg 66:
÷ or

12. Divide Numbers
Example: Example :
Example:

13. Divide Numbers Example # 80 pg 66: Remember:
We should write all fractions with the negative in front , this will be the class standard

14. Divide Numbers
Example:

15. Summary of Operation of Real Numbers
Page 64 Summarizes of Operation of Real Numbers
Addition
Subtraction
Multiplication
Division
This is a good chart to use as a study guide for a test.

16. Evaluate Divisions Involving 0
Zero Divided by a Nonzero Number
If a represents any real number except 0, then
Examples:

17. Evaluate Divisions Involving 0
Division by Zero
If a represents any real number except 0, then
Examples:

18. HOMEWORK 1.8
Page
17, 19, 26, 29, 33, 35, 43, 45, 51, 62, 63, 67, 95