2-1 Adding Integers Course 3 Warm Up Warm Up Problem of the Day Problem of the Day Lesson Presentation Lesson Presentation

Warm Up Graph each number on a number line Course Adding Integers Add

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? Course Adding Integers (–2, –2)

Learn to add integers. Course Adding Integers

Vocabulary integer opposite absolute value Insert Lesson Title Here Course Adding Integers

Course Adding Integers 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.

Course Adding Integers 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) –6 You finish at –4, so (–6) + 2 = –4. –6 –5 –4 –3 –2 –

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

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. Course Adding Integers 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.

Course Adding Integers 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; use the sign of 8. –3

Course Adding Integers 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

Course Adding Integers 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; use the sign of 4. –3

Course Adding Integers 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

Course Adding Integers 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

Course Adding Integers 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

Course Adding Integers 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 (–166) + (–38) Group integers with same signs. ( ) + (–166 + –38) Add integers within each group (–204) 220 > 204; use the sign of Katrina’s account balance after the first four transactions is $16.

Course Adding Integers 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 (–133) + (–65) Group integers with same signs. ( ) + (–133 + –65) Add integers within each group (–198) 270 > 198; use the sign of Michael’s account balance after the first four transactions is $72.

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

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 Course Adding Integers 5 dogs