2-3 Subtracting Integers Problem of the Day Add. 1. – –3 + (–4) (–5) (–4) 5. –6 + (–1)6. – –7 2 –1 –7 –5

2-3 Subtracting Integers Use a number line to find each difference. Additional Example 1A: Modeling Integer Subtraction 4 – 1 –2– –1 4 – 1 = 3 Start at 0. Move right 4 spaces. To subtract 1, move to the left.

2-3 Subtracting Integers Rules for Subtracting Integers: Add the opposite 1. copy 2. change 3. opposite 4. Follow the Rules of Adding Integers.

2-3 Subtracting Integers Additional Example 1B: Modeling Integer Subtraction 1 2 –6–5–4 –3 –2–1 0 Use a number line to find each difference. –3 – 1 –3–1 –3 – 1 = –4 Start at 0. Move 3 spaces left. To subtract 1, move to the left.

2-3 Subtracting Integers Additional Example 1C: Modeling Integer Subtraction Use a number line to find each difference. –2 – (–4) –4 –3 –2–1 0 –2 –(–4) –2 – (–4) = 2 Start at 0. Move left 2 spaces. To subtract –4, move to the right.

2-3 Subtracting Integers Check It Out: Example 1A Use a number line to find each difference. –4 –(–2) –4–3–2–1 0 –(–2) –4 –2

2-3 Subtracting Integers Check It Out: Example 1B Use a number line to find each difference. 5 – (–1) 6 7 – –6 5 –(–1)

2-3 Subtracting Integers Addition and subtraction are inverse operations—they “undo” each other. Instead of subtracting a number you can add its opposite.

2-3 Subtracting Integers Find each difference. Additional Example 2: Subtracting Integers by Adding the Opposite A. 5 – (–2) B. –3 – 7 –3 + (–7) –10 C. – 1 – (–8) – Add the opposite of –2. Add the opposite of 7. Add the opposite of –8.

2-3 Subtracting Integers Check It Out: Example 2 Find each difference. A. –1 –4 –1 –4 = 1 + (–4) = -5 B. –6 –3 –6 –3 = –6 + (–3) = -9 C. 5– (– 6) 5 – (– 6) = =11

2-3 Subtracting Integers Check It Out: Example 2 Find each difference. D. 7 – (–2) 7 – (–2) = = 9

2-3 Subtracting Integers Evaluate x – y for each set of values. Additional Example 3: Evaluating Expressions with Integers A. x = –3 and y = 2 x – y –3 – 2 = –3 + (–2) = –5 B. x = 4 and y = –6 x – y 4 – (–6) = = 10 Substitute for x and y. Add the opposite of 2. Substitute for x and y. Add the opposite –6.

2-3 Subtracting Integers Check It Out: Example 3 Evaluate x – y for each set of values. A. x = –4 and y = –3 x – y = –4 –(–3) = –4 + 3 = –1 B. x = 24 and y = 20 = = 44 x – y = 24 –(–20)

2-3 Subtracting Integers Additional Example 4: Temperature Application Find the difference between 32°F and –10°F. 32 – (–10) = 42 The difference in temperature is 42˚F. Add the opposite of –10.

2-3 Subtracting Integers Check It Out: Example 4 Find the difference between 8 °F and -5 °F 8 –(–5) = = 13 The difference is 13 °F.

2-3 Subtracting Integers Standard Lesson Quiz Lesson Quizzes Lesson Quiz for Student Response Systems

2-3 Subtracting Integers Lesson Quiz: Part I Use a number line to find the difference – 9 Find each difference. 2. –7 – 4 3. –3 – (–5) 4. Evaluate x – y + z for x = –4, y = 5, and z = –10. –11 –6 2 –19

2-3 Subtracting Integers Lesson Quiz: Part II 5. On January 1, 2002, the high temperature was 81˚F in Kona, Hawaii. The low temperature was – 29˚F in Barrow, Alaska. What was the difference between the two temperatures? 110˚F

2-3 Subtracting Integers 1. Identify the number line that helps to find the difference. 5 – 15 A. –20 B. –10 Lesson Quiz for Student Response Systems

2-3 Subtracting Integers 2. Identify the difference. –8 – 5 A. 13 B. 3 C. –3 D. –13 Lesson Quiz for Student Response Systems

2-3 Subtracting Integers 3. Identify the difference. –2 – (–6) A. –8 B. –4 C. 4 D. 8 Lesson Quiz for Student Response Systems

2-3 Subtracting Integers 4. Evaluate x – y + z for x = –6, y = 4, and z = –12. A. –22 B. –12 C. –10 D. –2 Lesson Quiz for Student Response Systems

2-3 Subtracting Integers Lesson Quiz for Student Response Systems 5. In January 2002, the mean temperature was –26 °F in McMurdo, Antarctica. The mean temperature was 37 °F in London. What was the difference between the two temperatures? A. –63 °F B. –52 °F C. 52 °F D. 63 °F