1. Warm Up
Graph each number on a number line.
1. –
3. –
–5 –4 –3 –2 –

2. Problem of the Day
Start at 0 on a number line. Move 5 units left and 3 units right. Where are you on the number line? –2

3. Learn to add integers.

4. Additional Example 1A: Using a Number Line to Add Integers
Use a number line to find the sum.
(–6) + 2 –6 2
–6 –5 –4 –3 –2 –
You finish at –4, so (–6) + 2 = –4.
To add a positive number move to the right. To add a negative number move to the left.
Helpful Hint

5. Additional Example 1B: Using a Number Line to Add Integers
Use a number line to find the sum.
–3 + (–6)‏ –6 –3
–9 –8 –7 –6 –5 –4 –3 –2 –
You finish at –9, so –3 + (–6) = –9.

6. –6 –5 –4 –3 –2 –1 0 1 2 3 4 5 Check It Out: Example 1A
Use a number line to find the sum.
(–3) + 7 –3 7
–6 –5 –4 –3 –2 –
You finish at 4, so (–3) + 7 = 4.

7. –6 –5 –4 –3 –2 –1 0 1 2 3 4 5 Check It Out: Example 1B
Use a number line to find the sum.
(–2) + 4 –2 4
–6 –5 –4 –3 –2 –
You finish at 2, so (–2) + 4 = 2.

9. Additional Example 2: Using Absolute Value to Add Integers
1 + (–2)‏
Think: Find the difference of 1 and –2 . –1
2 > 1; use the sign of 2.
B. (–8) + 5
(–8) + 5
Think: Find the difference of –8 and 5 . –3
8 > 5; use the sign of 8.

10. Additional Example 2: Using Absolute Value to Add Integers
C. (–2) + (–4)‏
(–2) + (–4)‏
Think: Find the sum of –2 and –4 .
Same sign; use the sign of the integers. –6

11. Check It Out: Example 2
Add.
A. 3 + (–6)‏
3 + (–6)‏
Think: Find the difference of 3 and –6 . –3
6 > 3; use the sign of 6.
B. (–4) + 1
(–4) + 1
Think: Find the difference of –4 and 1 . –3
4 > 1; use the sign of 4.

12. Check It Out: Example 2C
Add.
C. (–6) + (–7)‏
(–6) + (–7)‏
Think: Find the sum of –6 and –7 .
Same sign; use the sign of the integers.
–13

13. Additional Example 3: Evaluating Expressions with Integers
Evaluate c + 4 for c = –8.
c + 4
(–8) + 4
Replace c with –8.
Think: Find the difference of –8 and 4 .
–8 + 4 = –4
8 > 4; use the sign of 8.

14. Check It Out: Example 3
Evaluate d + 7 for d = –3.
d + 7
(–3) + 7
Replace d with –3.
Think: Find the difference of –3 and 7 .
–3 + 7 = 4
7 > 3; use the sign of 7.

15. Additional Example 4: Application
Meka opened a new bank account. Find her account balance after the first four transactions listed below.
Deposits: $200, $20 Withdrawals: $166, $38
Use a positive sign for deposits and a negative sign for withdrawals.
(–166) + (–38)‏
Use the Associative Property to group integers with same signs.
( ) + (–166 + –38)‏
220 + (–204)‏
Add integers within each group. 16
220 > 204; use the sign of 220.
Meka’s account balance after the first four transactions is $16.

16. Check It Out: Example 4
Michael opened a new bank account. Find his account balance after the first four transactions listed below.
Deposits: $175, $95 Withdrawals: $133, $65
Use a positive sign for deposits and a negative sign for withdrawals.
(–133) + (–65)‏
( ) + (–133 + –65)‏
Use the Associative Property to group integers with same signs.
270 + (–198)‏
Add integers within each group. 72
270 > 198; use the sign of 270.
Michael’s account balance after the first four transactions is $72.

17. Lesson Quizzes
Standard Lesson Quiz
Lesson Quiz for Student Response Systems

18. Lesson Quiz
Add.
1. –7 + (– 7) (–9) + (–2)‏
–14 4
Evaluate each expression for the given value of the variable.
r for r = – b + (–9) for b = –6 –2
–13
5. On Monday, a local dog shelter had six dogs. By Friday they had found homes for three, but took in two more. Then how many dogs were in the shelter?
5 dogs