Download Adding Integers

LESSON 2.2
Adding Integers
Goal: Add integers.
Warm-up:
1. What patterns can you describe when adding a negative number to a positive number?
2. Write three examples of adding negative numbers to positive numbers. Be sure to give the
answer for your examples.
3. What patterns can you describe when adding a negative number to a negative number?
4. Write three examples of adding negative numbers to negative numbers. Be sure to give the
answer for your examples
End of Warm-up 
Vocabulary
Additive inverse:
Inverse property of addition:
Identity property of addition:
EXAMPLE 1 - Adding Negative Integers
Rule:
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Find the sum.
a. -4 + (–9)
b. –7 +(- 8)
c. –5 + (–2)
Now You Try It! Find the sum.
1. -11 + (–6)
2. –10 + (-3)
3. –4 + (–8)
EXAMPLE 2 - Adding Integers with Different Signs
Rule:
Find the sum.
a. 4 + (–9)
b. –7 + 8
c. 5 + (–2)
Now You Try It! Find the sum.
4. -11 + 6
5. 10 + (-3)
6. –4 + 8
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EXAMPLE 3 - Adding More Than Two Integers
Rule:
a. 4 + (–9) +19 + (-5) =
b. –56 + 24 + (–164) =
c. –39 + (–62) + (-76) =
d. -10 + 5 + 19 + (-20) + (-12) + 10 =
EXAMPLE 4 - APPLICATION
Banking You start a bank account. The table shows the deposits and withdrawals of the account
during the first month. How much money is in the account at the end of the month?
January 2
$675
January 9
–$80
January 19
–$25
January 24
$168
January 30
–$40
ANSWER:
EXAMPLE 5 – Inverse Property of Addition
Rule:
a. 28 + (–28) =
b. -19 + 19 =
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EXAMPLE 6 – Identity Property of Addition
Rule:
a. 32 + 0 =
b. -53 + 0 =
Now You Try It!
7. 110 + 123 + (–68) + (–165)=
8. –240 + (–516) + 193 + 113=
9. -1050 + 0 =
10. 2,345 + (-2,345) =
11. You get on the elevator in a city building. Your elevator goes up 10 floors, goes down 5
floors, goes up another 13 floors and then goes down 7 floors. Write and evaluate an
addition expression to find the floor on which you exit.
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