1. N.S. 1.2 8/29/11 Adding and Subtracting Integers

2. Rule Two like signs become a positive sign +(+) 3+(+2) = 3 + 2 = 5 -(-) 6-(-3) = 6 + 3 = 9 Two unlike signs become a negative sign +(-) 7+(-2) = 7 - 2 = 5 -(+) 8-(+2) = 8 - 2 = 6

3. Adding Integers 1) When adding integers of the same sign, we add their values, and give the result the same sign. Examples: 2 + 5 = 7 (-7) + (-2) = -(7 + 2) = -9 (-80) + (-34) = -(80 + 34) = -114

4. 2) When adding integers of the opposite signs, we turn the numbers into positive, subtract the smaller from the larger, and give the result the sign of the larger number. Example: 8 + (-3) = ? So, 8 and -3 become 8 and 3. Subtracting the smaller from the larger gives 8 - 3 = 5, and since the larger number was +8, we give the result the same sign as 8, so 8 + (-3) = 5.

5. Example: -22 + 11 = ? -22 and 11 become 22 and 11. Subtracting the smaller from the larger gives 22 - 11 = 11, and since the larger number is -22, we give the result the same sign as -22, so -22 + 11 = -11.

6. Subtracting IntegersWhen subtracting integers, add the opposite. 12 - (-5) = 12 + (5) = ____ -8 - 7 = -8 + (-7) = ____ -22 - (-40) = -22 + (40) = ____

7. Whiteboard CFU 38+(-5)=

8. Whiteboard CFU (-1)-(-40)=

9. Whiteboard CFU (-34)+50=

10. Whiteboard CFU 10+3-(-8)=

11. Whiteboard CFU 2- (-9)-8=

12. Independent Practice N.S. 1.2 Find each sum. 1. (-12) + 7  3. (-6)+12 4. -3+4   7. (-1) + (-46)=  Find each difference. 9. 2-(-2)= 0= 1 12. 4-11= 13. 48-(-31)= 14. 16-21= 15. 18-41 6 7) Evaluate each expression. 18. (-10) - 47= 19. 13+(-29) 0 1 2 3