1. 2-1 Adding Integers Pre-Algebra Warm Up Warm Up Problem of the Day Problem of the Day Lesson Presentation Lesson Presentation

2. Warm Up Graph each number on a number line. 1. 52. 7 3. 44. 0 Pre-Algebra 2-1 Adding Integers 0 1 2 3 4 5 6 7 8 9 10 41 35 Add. 5. 22 + 19 6. 17 + 18

3. Problem of the Day Start at (0, 0). Walk 3 blocks west and 2 blocks north. Then walk 4 blocks south and 1 block east. What are your coordinates? (–2, –2) Pre-Algebra 2-1 Adding Integers

4. Learn to add integers. Pre-Algebra 2-1 Adding Integers

5. Vocabulary integer opposite absolute value Insert Lesson Title Here Pre-Algebra 2-1 Adding Integers

6. -5 -4 -3 -2 -1 0 1 2 3 4 5 Negative integers Positive integers 0 is its own opposite –3 and 3 are opposites Integers are sets of whole numbers, including 0, and their opposites. The sum of two opposite integers is zero. Pre-Algebra 2-1 Adding Integers

7. To add a positive number move to the right. To add a negative number move to the left. Helpful Hint Additional Example 1: Using a Number Line to Add Integers Use a number line to find the sum. (–6) + 2 2 –6 You finish at –4, so (–6) + 2 = –4. –6 –5 –4 –3 –2 –1 0 1 2 3 4 5 Pre-Algebra 2-1 Adding Integers

8. Try This: Example 1 Use a number line to find the sum. (–3) + 7 7 –3 You finish at 4, so (–3) + 7 = 4. –6 –5 –4 –3 –2 –1 0 1 2 3 4 5 Pre-Algebra 2-1 Adding Integers

9. Another way to add integers is to use absolute value. The absolute value of a number is its distance from 0. The absolute value of –4, written as |–4|, is 4; and the absolute value of 5 is 5. Adding integers If the signs are the same...If the signs are different... find the sum of the absolute values. Use the same sign as the integers. find the difference of the absolute values. Use the sign of the integer with the larger absolute value. Pre-Algebra 2-1 Adding Integers

10. Additional Example 2A & 2B: Using Absolute Value to Add Integers A. 1 + (–2) Think: Find the difference of 2 and 1. Add. 1 + (–2) 2 > 1; use the sign of 2. –1 B. (–8) + 5 Think: Find the difference of 8 and 5.(–8) + 5 8 > 5; use the sign of 8. –3 Pre-Algebra 2-1 Adding Integers

11. Additional Example 2C: Using Absolute Value to Add Integers C. (–2) + (–4) Think: Find the sum of 2 and 4. Add. (–2) + (–4) Same sign; use the sign of the integers. –6 Pre-Algebra 2-1 Adding Integers

12. Try This: Example 2A & 2B A. 3 + (–6) Think: Find the difference of 6 and 3. Add. 3 + (–6) 6 > 3; use the sign of 6. –3 B. (–4) + 1 Think: Find the difference of 4 and 1.(–4) + 1 4 > 1; use the sign of 4. –3 Pre-Algebra 2-1 Adding Integers

13. Try This: Example 2C C. (–6) + (–7) Think: Find the sum of 6 and 7. Add. (–6) + (–7) Same sign; use the sign of the integers. –13 Pre-Algebra 2-1 Adding Integers

14. Additional Example 3: Evaluating Expressions with Integers Evaluate c + 4 for c = –8. c + 4 Replace c with –8. Think: Find the difference of 8 and 4. 8 > 4; use the sign of 8. (–8) + 4 –8 + 4 = –4 Pre-Algebra 2-1 Adding Integers

15. Try This: Example 3 Evaluate d + 7 for d = –3. d + 7 Replace d with –3. Think: Find the difference of 7 and 3. 7 > 3; use the sign of 7. (–3) + 7 –3 + 7 = 4 Pre-Algebra 2-1 Adding Integers

16. Additional Example 4: Application Katrina 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. 200 + 20 + (–166) + (–38) Group integers with same signs. (200 + 20) + (–166 + –38) Add integers within each group. 220 + (–204) 220 > 204; use the sign of 220. 16 Katrina’s account balance after the first four transactions is $16. Pre-Algebra 2-1 Adding Integers

17. Try This: 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. 175 + 95 + (–133) + (–65) Group integers with same signs. (175 + 95) + (–133 + –65) Add integers within each group. 270 + (–198) 270 > 198; use the sign of 270. 72 Michael’s account balance after the first four transactions is $72. Pre-Algebra 2-1 Adding Integers

18. Lesson Quiz: Part 1 Add. 1. –7 + (– 7) 2. 15 + (–9) + (–2) 4 –14 Insert Lesson Title Here Evaluate each expression for the given value of the variable. 3. 13 + r for r = –15 4. 2 + b + (–9) for b = –6 –2 –13 Pre-Algebra 2-1 Adding Integers

19. Lesson Quiz: Part 2 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? Insert Lesson Title Here 5 dogs Pre-Algebra 2-1 Adding Integers