11-3: Subtracting Integers

1. 11-3: Subtracting Integers The University of Texas at Dallas

2. 2 ways to help you subtract integers. 1. Use Color Counters 2. Mentally

3. SUBTRACTING INTEGERS (using color counters) • We often think of subtraction as a “take away” operation. • Which diagram could be used to compute +3 - +5 = ? +3 +3 The University of Texas at Dallas

4. SUBTRACTING INTEGERS (using color counters) • This diagram shows adding 2 zero pairs. • Now we can take 5 yellow tiles away, we have 2 red tiles left. We can’t take away 5 yellow tiles from this diagram. There is not enough tiles to take away!! The University of Texas at Dallas

5. SUBTRACTING INTEGERS (using color counters) • Use your red and yellow tiles to model each subtraction problem. -2 - -4 = ? ANSWER The University of Texas at Dallas

6. SUBTRACTING INTEGERS Now you can take away 4 red tiles. 2 yellow tiles are left, so the answer is… This representation of -2 doesn’t have enough tiles to take away -4. If you add 2 zero pairs(adding zero) you would have a total of 4 red tiles and the tiles still represent -2. -2 - -4 = +2 The University of Texas at Dallas

7. SUBTRACTING INTEGERS (using color counters) Work this problem. +3 - -5 = ? ANSWER The University of Texas at Dallas

8. SUBTRACTING INTEGERS • Add enough zero pairs so you can take away 5 red tiles. • Take away 5 red tiles, you have 8 yellow tiles left. +3 - -5 = +8 The University of Texas at Dallas

9. SUBTRACTING INTEGERS (using color counters) Work this problem. -3 - +2 = ? ANSWER The University of Texas at Dallas

10. SUBTRACTING INTEGERS • Add two zero pairs so you can take away 2 yellow tiles. • Take away 2 yellow tiles, you have 5 red tiles left. -3 - +2 = -5 The University of Texas at Dallas

11. Subtracting Integers Mentally, then check using color counters. When you subtract integers you…….. ADD the OPPOSITE!!!! 9 – (-2) +3 – (-1) -5 – (-8) -7 - 6

12. Practice Time  P 585 # 1-7