Lesson 1.5 Adding Integers

1. Lesson 1.5 Adding Integers

2. Vocabulary Absolute Value- The distance a number is from zero. *Always positive Example: |-9| = 9 |9| = 9 Opposites- Have the same absolute value but different signs. 6 and -6 are opposites -30 and 30 are opposites

3. Adding Integers Rule #1 If the numbers have the same sign, find the sum of the absolute values and keep the common sign. Examples: 5 + 6 = |5| + |6| = 11 - 4 + (-3) = - 7 because 4 + 3 = 7 and both signs are negative so the final answer is negative. -20 + (-10) = -30 because 20 + 10 = 30 and both signs are negative so the final answer is negative.

4. Practice 1.) -7 + (-8) 2.) -15 + (-2) 3.) -36 + (-5)

5. Adding Integers Rule #2 If the signs are different, find the difference of the absolute values and keep the sign of the bigger number. Examples: -10 + 4 = -6 because 10 – 4 = 6 and 10 is bigger than 4 and 10 was negative. 7 + (-9) = -2 because 9 – 7 = 2 and 9 is bigger than 7 and 9 was negative. -11 + 20 = 9 because 20 – 11 = 9 and 20 is bigger than 11 and 20 was positive

6. Practice 1.) – 25 + 6 2.) 30 + (-9) 3.) -22 + 55

7. Adding Integers Rule #3 The sum of a number and its opposite is 0. Examples: - 9 + 9 = 0 8 + (-8) = 0 -25 + 25 = 0

8. Lesson 1.6 Subtracting Integers

9. Subtracting Rule To subtract integers, add the opposite of the second number. Then follow one of the three adding rules. Examples: -12 – 2 = -14 because -12 + (-2) follows adding rule #1. 12 + 2 = 14 and both signs are negative so the final answer is negative. -8 – (-10) = 2 because -8 +10 follows adding rule #2. 10 – 8 = 2 and 10 is bigger than 8 and 10 is positive.

10. Practice 1.) 4 – 10 2.) 7 – (-5) 3.) – 2 – (-9)

11. 4.) 2 – 6 5.) 3 – (-8) 6.) -7 - 4