1. 1
Introduction to Algebra:
Integers

2. R.1 Fractions
1.3 Adding Integers
Objectives
Add integers.
Identify properties of addition.

3. Add integers.
Numbers that you add together are called addends, and the result is called a sum.

4. Add integers.
Use a number line to find 5 + (4) (use a football analogy).
Example

5. Add integers.

6. Add integers. Example Add the integers 8 + (7).
Step 1 Add the absolute values.
|8| = 8 and |7| = 7
Add to get 15.
Step 2 Use the common sign as the sign of the sum.
8 + 7= 15
Both negative Sum is negative

7. Add integers.
Adding Two Integers with Unlike Signs
Step 1 Subtract the lesser absolute value from the greater absolute value.
Step 2 Use the sign of the number with the greater absolute value as the sign of the sum.

8. Add integers. Example Add the integers 8 + 3.
Step 1 |3| = 3 and |8| = 8
Subtract 8 – 3 to get 5.
Step 2 8 has the larger absolute value and is negative, so the sum is also negative.
8 + 3 = 5

9. Add integers.
A football team has to gain at least 10 yards during four plays in order to keep the ball. Suppose on four plays a team lost 6 yards, gained 8 yards, lost 2 yards, and gained 7 yards. Did the team gain enough to keep the ball?
Example

10. Add integers.
(continued)
Example

11. Identify properties of addition.
Addition Property of 0
Adding 0 to any number leaves the number unchanged.
Some examples are shown below.
0 + 6 =  = 25
72, = 72, (100)= 100

12. Identify properties of addition.
Commutative Property of Addition
Changing the order of two addends does not change the sum.
Here are some examples.
=  = 6 + (10)
Both sums are 86 Both sums are 4

13. Identify properties of addition.

14. Identify properties of addition.
Add  using the associative property.
Group 9 and 9 because the sum is 0.
Example