over lesson 2–2 a.a b.b c.c d.d 5-minute check 1 a.–7 b.–1 c.1 d.7 find –4 + (–3). find...
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Over Lesson 2–2
A. A
B. B
C. C
D. D
A. –7B. –1C. 1D. 7
Find –4 + (–3).
Find –14 + 20.A. –34B. –6C. 6D. 34Find 2 + (–6) + 9.A. –5B. 5C. –17D. 17
You have already learned to subtract integers using algebra tiles. (Explore 2–3)
• Subtract integers.
• Evaluate expressions containing variables.
In other words, change the subtract sign to addition and change the sign of the number after the subtraction sign (we say “add the opposite!”)
Subtract a Positive Integer
A. Find 9 – 14.
9 – 14 = 9 + (–14) To subtract 14, change to add –14 .
= –5 Simplify.
Answer: –5
B. Find –10 – 8.
–10 – 8 = –10 + (–8) To subtract 8, change to add –8.
= –18 Simplify.
Answer: –18
Subtract a Positive Integer
A. A
B. B
C. C
D. D
A. 2
B. –2
C. –3
D. 14
A. Find 6 – 8.
A. A
B. B
C. C
D. D
A. –22
B. –4
C. 4
D. 22
B. Find –9 – 13.
Subtract a Negative Integer
A. Find 15 – (–4).
15 – (–4) = 15 + 4 To subtract –4, change to add 4.
= 19 Simplify.
Answer: 19
B. Find –11 – (–7).
–11 – (–7) = –11 + 7 To subtract –7, change to add 7.
= –4 Simplify.
Answer: –4
Subtract a Negative Integer
A. A
B. B
C. C
D. D
A. 6
B. 10
C. –6
D. 16
A. Find 8 – (–2).
A. A
B. B
C. C
D. D
A. 17
B. 7
C. –17
D. –7
B. Find –12 – (–5).
Subtract a Negative Integer
WEATHER The wind makes the outside temperature feel colder than the actual temperature. How much colder does a temperature of 0°F with a 20-mile-per-hour wind feel than the same temperature with a 10-mile-per-hour wind?
Understand You need to find how much colder 0° feels with a 20-mile-per-hour wind than with a 10-mile-per-hour wind.
Subtract a Negative Integer
Plan Subtract the wind chill temperature at 20 miles per hour from the wind chill temperature at 10 miles per hour.
Answer: It feels 6 degrees colder.
Solve –22 – (-16) = –22 + 16To subtract –16, add 16.
= –6Add –22 and 16.
Check Since –22 < –16, it makes sense that the temperature is colder.
A. A
B. B
C. C
D. D
A. 5 degrees colder
B. 7 degrees colder
C. 8 degrees colder
D. 10 degrees colder
WEATHER How much colder does a temperature of 0° feel with a 30-mile-per-hour wind than the same temperature with a 10-mile-per-hour wind?
Evaluate Algebraic Expressions
Evaluate x – y + z if x = 4, y = –5, and z = –14.
Answer: –5
x – y + z =4 – (–5) + (–14) Replace x with 4, y with –5, and z with –14.
= 9 + (–14) Use order of operations.
= –5 Add 9 and –14.
A. A
B. B
C. C
D. D
A. –12
B. –6
C. 6
D. –27
Evaluate m – n if m = –9 and n = –3.
