3.4+“Undoing”+with+Addition+And+Subtraction

18.05.09 LW

Big Idea Negative numbers help us to model many real world situations. Investigation 3: Subtracting Integers Essential Question #3: How do I find the difference between integers?



1. Complete the addition sentence -17+13=?.** -17+13=-4
 * A.
 * 2. Write a subtraction sentence that "undoes" the addition sentence you found in part 1.**
 * 4-(-13)=17

B. 1. Complete the addition sentence -4+-18=?. -4+(-8)= -22 ****2. Write a subtraction sentence that " undoes " the addition sentence you found in part 1. 22-4=18 ****

C. Write a subtraction sentence that solves each problem. 1.** **?+-18=** **6 (?=24) ** 24-6=18 -28-(-41)=13 3.2-9.3=-6.1 1/3-(-1/3) = 2/3 0+(-6)=-6 -1+3=2 7.1+(-5.3)=1.8 -1- (-3/4)=-1/4
 * 2. ?+-13=-41** **(?= -28) **
 * 3. ?+6.1=-3.2** **(?=-9.3) **
 * 4. ?+(-1/3)=** **1/3** **(?=2/3) **
 * D. Write an addition sentence that solves each problem.**
 * 1. ?-(-6)=-6** **(?= 0) **
 * 2. ?-(-2)=3** **(?=1) **
 * 3. ?-5.3=-7.1** **(?=-1.8)**
 * 4. ?- (-1/4)= -3/4** **(?=-1) **


 * __Follow up__

**1. Can you write a different subtraction sentence to go with 3+11=14?
 * 14-11=3

****2. a. Complete the addition sentence 3.8+-2.6=?** 3.8+-2.6=1.2

3.8-1.2=2.6 **
 * b. Write a subtraction sentence that is related to the addition sentence you found in part a.

**3. a. Complete the subtraction sentence -11-6=?.** -11-6=-17

-17+6=-11 **
 * b. Write a addition sentence that is related to the subtraction sentence you found in part a.

4. When you add positive and a negative integers, sometimes you get a positive sum and sometimes you get a negative sum. Is the same true when you subtract positive and negative integers? Explain.** Yes, because it depends on the numbers that you subtract and if they are positive or negative. Ex: 24-(-2)= 26 -2-24=-26