Download Pre-Algebra

Algebra I
Chapter 2-5 and 2-6
Multiplying and Dividing Integers
Group Work
• You own shares of stock in a computer company and in
a utility. The value of the shares changes over time.
The table shows the number of shares of each type of
stock you own and the change in the value of each share
over a one-year period. What was the total change in
the value of your shares of stock?
Stock Portfolio
Stock
Shares
Computer 200
Utilities
150
Change in value of one
share
Decreased $3
Increased $2
Multiplying and Dividing Integers
• Same Sign?
Positive answer
– Even number of negatives
• Different Sign?
Negative answer
– Odd number of negatives
Examples
• -3(-12)(-2)
• -7(9)(-1)
• -24(231)(0)
Examples
• -48 ÷ (-6) ÷ -1
• 56 ÷ (-8) ÷ -2
•0÷9
Examples
• -6 [(-5) + (-7)]
• 8[17 – (-3)](1/4)
• -(3³) • [-(2³)]
Try This
• 4(2³) • [-(3³)] • 6
• (-2)³
• (-1)
23
Reciprocal
• Two rational numbers whose product is 1
are called multiplicative inverses or
reciprocals of each other.
What is the reciprocal of 8/9?
• What’s the reciprocal of m/n?
• 0.8?
REWRITE AS MULTIPLICATION
PROBLEM
• -4 ÷ 3 = -4 (1/3)
• x + 2 = (x+2) (1/5)
5
-17 = -17 (b)
1/b
Try this
• Page 83 n – u
• Write the rule for dividing numbers
• Write the Property of Multiplicative Inverse
on page 82
• Do #28 – 42 on page 84
Find the Mean
• The table shows record low monthly
temperatures from June to November at
McMurdo Station in Antarctica. Find the mean
of the temperatures.
Month June
July
Aug.
Sept.
Oct.
Nov.
Temp -42
-59
-57
-47
-40
-19