Transcript Lesson 2-6B PowerPoint

(over Lesson 2-5)
Evaluate c – b for b = 3 and c = –1.
A. 4
B. 2
C. –2
D. –4
Evaluate 9 – a for a = –2.
A. 11
B. 7
C. –7
D. –11
What is –4 subtracted from –3?
A. –7
B. –1
C. 1
D. 7
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2.
3.
4.
A
B
C
D
Main Idea
Key Concept: Multiply Integers with Different Signs
Key Concept: Multiply Integers with Same Sign
Example 6: Use Integers to Solve a Problem
Example 7: Evaluate Expressions
• Multiply integers (2.2.8B) (M8.A.3.3.1).
1.
D
Use Integers to Solve a Problem
MINES A mine elevator descends at a rate of
300 feet per minute. How far below the earth’s
surface will the elevator be after 5 minutes?
If the elevator descends 300 feet per minute, then after
5 minutes, the elevator will be at –300(5) or –1,500 feet.
Thus, the elevator will descend to –1,500 feet.
Answer: After five minutes, the elevator will be
1,500 feet below the earth’s surface.
RETIREMENT Mr. Rodriguez has $78 deducted from
his pay every month and placed in a savings account
for his retirement. What integer represents a change
in his savings account for these deductions after six
months?
A. –$468
B. $468
C. –$84
D. $84
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2.
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4.
A
B
C
D
Evaluate Expressions
ALGEBRA Evaluate abc if a = –3, b = 5, and c = –8.
abc = (–3)(5)(–8)
Replace a with –3, b with 5,
and c with –8.
= (–15)(–8)
Multiply –3 and 5.
= 120
Multiply –15 and –8.
Answer: 120
ALGEBRA Evaluate xyz if x = –6, y = –2, and z = 4.
A. –48
B. –4
C. 0
D. 48
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A
B
C
D
REVIEW
1. Tamera owns 100 shares of a certain stock.
Suppose the price of the stock drops by $3 per
share. Write a multiplication expression to find the
change in Tamera’s investment. Explain.
100(-3) = -300; Tamera’s investment if
now worth $300 less than it was
before the stock dropped.
Evaluate each expression if f = -1, g = 7, and h = -10.
5(-1)=-5
2. 5f
3. fgh
-1(7)(-10)=70
End of the Lesson
Five-Minute Check (over Lesson 2–5)
Image Bank
Math Tools
Adding Integers
Comparing and Ordering Integers
Subtracting Positive and Negative Integers