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...

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.