1. Bellwork Oct. 1, 2010 Add. 1. –2 + 62. –3 + (–4) 3. 7 + (–5)4. 3 + (–4) 5. –6 + (–1)6. –6 + 1 4 –7 2 –1–1 –7–7 –5 SAME SIGN=SUM DIFFERENT SIGNS=DIFFERENCE

2. 2-3 Subtracting Integers Pg. 88

3. Essential Question  How do you subtract a negative integer?

4. A submarine is 58 feet below sea level. An airplane is 264 above sea level. How far above the submarine is the airplane?

5. The daytime high temperature on the Moon can reach 130 degrees Celsius. At night, the temperature can drop to -110 degrees Celsius. What is the difference between the high and low temperatures?

6.  A music recording company made a net profit of $20,000 in 2009 and had a net loss of $12,000 in 2010. How much did the company’s profits change from 2009-2010?

7. Subtracting Integers Video Clip  Write down 3 facts about subtracting integers. 1. 2. 3.

8. Practice with the Professor  http://my.hrw.com/math06_07/nsme dia/homework_help/msm2/msm2_ch 02_03_homeworkhelp.html

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

10. SAME CHANGE CHANGE 1.SAME: Leave the first number alone. 2.CHANGE: Change the sign in the middle from a subtraction sign to an addition sign 3.CHANGE: Change the sign of the second number.

11. Same- Change- Change -3 – 2 = Same Change - 5

12. -4 - 3 = -7 Same Change EXAMPLE:

13. Find each difference. Example 1 A. 5 – (–2) 5 + 2 7 B. –3 – 7 –3 + (–7) –10 C. – 1 – (–8) –1 + 8 7

14. Find each difference. A. 4 – 2 4 + (–2) 2 B. –2 – (–6) –2 + 6 4 C. –1 – 4 –1 + (–4) –5 Example 2

15. Practice

16. 6 + -10 Think: 10 – 6 = 4 Largest #: 10 Sign: - Answer: -4 -3 + 8 Think: 8-3 = 5 Largest #: 8 Sign: + Answer: 5

17. Integer War  Take out the face cards  Red is negative  Black is positive  Divide the stack of cards in half  Each person flip over a card at the same time  Decide which person will be the first number in the subtraction problem.  Find the difference of the cards.  Write down each problem and answer on your paper.  Whoever answers first gets the cards  Keep track of your points