c2_ch02_04.pptc2_ch02_04.pptc2_ch02_04.ppt
- 1. 2-4 Multiplying and Dividing Integers Course 2 Warm Up Warm Up Problem of the Day Problem of the Day Lesson Presentation Lesson Presentation
- 2. Warm Up Evaluate each expression. 1. 17 · 5 2. 8 · 34 3. 4 · 86 4. 20 · 850 5. 275 ÷ 5 6. 112 ÷ 4 85 272 344 Course 2 2-4 Multiplying and Dividing Integers 17,000 55 28
- 3. Problem of the Day A teacher assigns 5 points for a correct answer, and –2 points for an incorrect answer, and 0 points for leaving the questioned unanswered. What is the score for a student who had 22 correct answers, 15 incorrect answers, and 7 unanswered questions? 80 Course 2 2-4 Multiplying and Dividing Integers
- 4. Learn to multiply and divide integers. Course 2 2-4 Multiplying and Dividing Integers
- 5. Course 2 2-4 Multiplying and Dividing Integers You can think of multiplication as repeated addition. 3 · 2 = 2 + 2 + 2 = 6 and 3 · (–2) = (–2) + (–2) + (–2) = –6
- 6. Use a number line to find each product. Additional Example 1A: Multiplying Integers Using Repeated Addition Course 2 2-4 Multiplying and Dividing Integers –7 · 2 + (–7) + (–7) –7 · 2 = 2 · (-7) Use the Commutative Property. -14 -13 -12 -11 -10 -9 -8 -7 -6 -5 -4 -3 -2 -1 0 Think: Add -7 two times. –7 · 2 = –14
- 7. Use a number line to find each product. Additional Example 1B: Multiplying Integers Using Repeated Addition Course 2 2-4 Multiplying and Dividing Integers –8 · 3 –8 · 3 = 3 · (–8) –8 · 3 = –24 Think: Add –8 three times. Use the Commutative Property. + (–8) + (–8) + (–8) –24–23–22–21–20–19–18–17-16-15-14-13 -12 -11 -10 -9 -8 -7 -6 -5 -4 -3 -2 -1 0
- 8. Use a number line to find each product. Check It Out: Example 1A Course 2 2-4 Multiplying and Dividing Integers –3 · 2 + (–3) + (–3) –3 · 2 = 2 · (-3) Use the Commutative Property. -14 -13 -12 -11 -10 -9 -8 -7 -6 -5 -4 -3 -2 -1 0 Think: Add -3 two times. –3 · 2 = –6
- 9. Use a number line to find each product. Check It Out: Example 1B Course 2 2-4 Multiplying and Dividing Integers –5 · 3 –5 · 3 = 3 · (–5) –5 · 3 = –15 Think: Add –5 three times. Use the Commutative Property. + (–5) + (–5) + (–5) -15 -14 -13 -12 -11 -10 -9 -8 -7 -6 -5 -4 -3 -2 -1
- 10. Course 2 2-4 Multiplying and Dividing Integers Multiplication and division are inverse operations. They “undo” each other. Notice how these operations undo each other in the patterns shown. Remember!
- 11. Course 2 2-4 Multiplying and Dividing Integers The patterns below suggest that when the signs of integers are different, their product or quotient is negative. The patterns also suggest that the product or quotient of two negative integers is positive.
- 12. Course 2 2-4 Multiplying and Dividing Integers MULTIPLYING AND DIVIDING INTEGERS MULTIPLYING AND DIVIDING INTEGERS If the signs are: Your answer will be: the same different positive negative
- 13. Find each product. Additional Example 2: Multiplying Integers Course 2 2-4 Multiplying and Dividing Integers A. –6 · (–5) –6 · (–5) Both signs are negative, so the product is positive. 30 B. –4 · 7 –4 · 7 The signs are different, so the product is negative. -28
- 14. Find each product. Check It Out: Example 2 Course 2 2-4 Multiplying and Dividing Integers A. –2 · (–8) –2 · (–8) Both signs are negative, so the product is positive. 16 B. –3 · 5 –3 · 5 The signs are different, so the product is negative. –15
- 15. Find each quotient. Additional Example 3: Dividing Integers Course 2 2-4 Multiplying and Dividing Integers A. 35 ÷ (–5) 35 ÷ (5) –7 B. –32 ÷ (–8) 32 ÷ (–8) 4 Think: 35 ÷ 5 = 7. The signs are different, so the quotient is negative. Think: 32 ÷ 8 = 4. The signs are the same, so the quotient is positive.
- 16. Additional Example 3: Dividing Integers Course 2 2-4 Multiplying and Dividing Integers Find the quotient. C. –48 ÷ 6 –48 ÷ 6 8 Think: 48 ÷ 6 = 8. The signs are different, so the quotient is negative.
- 17. Check It Out: Example 3 Insert Lesson Title Here Course 2 2-4 Multiplying and Dividing Integers Find each quotient. A. –12 ÷ 3 –12 ÷ 3 –4 B. 45 ÷ (–9) 45 ÷ (–9) –5 Think: 12 ÷ 3 = 4. The signs are different, so the quotient is negative. Think: 45 ÷ 9 = 5. The signs are different, so the quotient is negative.
- 18. Check It Out: Example 3 Insert Lesson Title Here Course 2 2-4 Multiplying and Dividing Integers Find the quotient. C. –25 ÷ (–5) –25 ÷ –5 5 Think: 25 ÷ 5 = 5. The signs are the same, so the quotient is positive.
- 19. Mrs. Johnson kept track of a stock she was considering buying. She recorded the price change each day. What was the average change per day? Additional Example 4: Averaging Integers Course 2 2-4 Multiplying and Dividing Integers Day Mon Tue Wed Thu Fri Price Change ($) –$1 $3 $2 –$5 $6 (–1) + 3 + 2 + (–5) + 6 = 5 Find the sum of the changes in price. 5 ÷ 5 = 1 The average change was $1 per day. Divide to find the average.
- 20. Check It Out: Example 4 Insert Lesson Title Here Course 2 2-4 Multiplying and Dividing Integers Mr. Reid kept track of his blood sugar daily. He recorded the change each day. What was the average change per day? (–8) + 2 + 4 + (–9) + 6 = –5 Find the sum of the changes in blood sugar. –5 ÷ 5 = –1 The average change per day was –1 unit. Divide to find the average. Day Mon Tue Wed Thu Fri Unit Change –8 2 4 –9 6
- 21. Lesson Quiz: Part I Use a number line to find the product. 1. –8 · 2 Find each product or quotient. 2. –3 · 5 · (–2) 3. –75 ÷ 5 4. –110 ÷ (–2) –16 Insert Lesson Title Here –15 55 Course 2 2-4 Multiplying and Dividing Integers 30
- 22. Lesson Quiz: Part II 5. The temperature at Bar Harbor, Maine, was –3°F. It then dropped during the night to be 4 times as cold. What was the temperature then? Insert Lesson Title Here Course 2 2-4 Multiplying and Dividing Integers –12°F