# 1 Bellwork Oct. 7, 2010 Evaluate each expression. 1. 17 · 5 2. 8 · 34 3. 4 · 86 4. 20 · 850 5. 275 ÷ 5 6. 112 ÷ 4 85 272 344 17,000 55 28.

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1 Bellwork Oct. 7, 2010 Evaluate each expression. 1. 17 · 5 2. 8 · 34 3. 4 · 86 4. 20 · 850 5. 275 ÷ 5 6. 112 ÷ 4 85 272 344 17,000 55 28

2 Focus Lesson -2.4 + 3.6 + 9 -2.4 + 3.6 + 9

3 2-4 Multiplying & Dividing Integers Pg. 94

4 Essential Question How are multiplying and dividing integers similar? How are multiplying and dividing integers similar?

5 Negatives in _______ are __________; ________ in pairs, theyre ________. Negatives in _______ are __________; ________ in pairs, theyre ________. WELCOME TO THE PARTY IN MATHLAND!! WELCOME TO THE PARTY IN MATHLAND!! See if you can fill in the blanks as you listen to the story

6 The Party in Mathland Everyone is happy and having a good time (they are ALL POSITIVE). Suddenly, who should appear but the GROUCH (ONE NEGATIVE)! The grouch goes around complaining to everyone about the food, music, the room temperature, the other people.

77 What happens to the party? Everyone feels a lot less happy…the party may be doomed!! ONE NEGATIVE MAKES EVERYTHING NEGATIVE!!! ONE NEGATIVE MAKES EVERYTHING NEGATIVE!!!

8 But wait…is that another guest arriving? What if another grouch (A SECOND NEGATIVE) appears? The 2 negative grouches pair up and gripe and moan to each other what a horrible party it is and how miserable they are!! But look!! They are starting to smile; theyre beginning to have a good time themselves!!

99 Now that the two grouches are together the rest of the people (who were really positive all along) become happy once again. The party is saved!!! PAIRS OF NEGATIVES BECOME POSITIVE PAIRS OF NEGATIVES BECOME POSITIVE

10 Negatives in PAIRS are POSITIVE; NOT in pairs, theyre NEGATIVE.

11 So you never get mixed up…. Make a tic tac toe board……fill it in like this. Make a tic tac toe board……fill it in like this. + stands for positive numbers, the - for negative numbers + stands for positive numbers, the - for negative numbers+___+_ __+

12 You can think of multiplication as repeated addition. 3 · 2 = 2 + 2 + 2 = 6 and 3 · (–2) = (–2) + (–2) + (–2) = –6

13 Use a number line to find each product. Example 1 – 7 · 2 + (–7) + (–7) –7 · 2 = 2 · (-7) -14 -13 -12 -11 -10 -9 -8 -7 -6 -5 -4 -3 -2 -1 0 –7 · 2 = –14

14 Multiplication and division are inverse operations. They undo each other. Notice how these operations undo each other in the patterns shown. Remember!

15 MULTIPLYING AND DIVIDING INTEGERS If the signs are:Your answer will be: the same different positive negative

16 Find each product. Example 2 A. –6 · (–5) –6 · (–5) 30 B. –4 · 7 –4 · 7 -28

17 Find each quotient. Example 3 A. 35 ÷ (–5) 35 ÷ ( 5) –7 B. –32 ÷ (–8) 32 ÷ (–8) 4

18 Multiplying and Dividing Integers Video Clip

19 Practice

20 Practice -1028

21 Practice -8 4

22 Work Session Textbook Textbook Page 96 Page 96 18-42 EVEN ONLY 18-42 EVEN ONLY GRADED GRADED

23 Homework Workbook Workbook Page 16 Page 16 All problems All problems STUDY-TEST TOMORROW ON INTEGERS STUDY-TEST TOMORROW ON INTEGERS

24 Closing Find each product or quotient. 1. –3 · 5 · (–2) 2. –75 ÷ 5 3. –110 ÷ (–2) –15 55 30

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