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2.4and2.5.notebook
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25: Subtracting IntegersWelcome! Please have your homework assignment on your desk.You have 3 minutes to complete the problems below.
5.
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24: Adding IntegersMain Idea: add integersVocabulary:• opposites two integers are opposite if they are represented on the number line by points that are the same distance from zero, but on opposite sides of zero. The sum of two opposites is zero. • additive inverse the opposite of an integer. The of an integer and its additive inverse is zero.
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-8 + 5 = -8 + 5 =
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7 + -5 =
Put colored chips into the "bowl" to represent the equation and then solve.
2Answer
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-6
2 + -8 =
Answer
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0
4 + -4 =
Answer
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Adding Integers-3 + -2 =
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-5 + 3
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Adding integers with the same sign
Adding integers with different signs
-2 + -7 = -5 + 9 =Add the two numbers and keep the same sign
Subtract the two numbers and keep the sign of the number with the larger absolute value
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Subtracting Integers, it is as easy as adding.... in fact you have to change it into an addition problem.
Hailey owed $200 on her credit card. She made another purchase of $20 how much does she now owe?
200 20
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Steps to solve:
1. Leave the first number alone.
2. Change the minus sign to a plus
3. Use the OPPOSITE of the second number
200 20
200 + 20
200 + (20)
SAME
CHANGE
OPPOSITE
200 20
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SAME CHANGE OPPOSITE
+++
+
121.2.
3.4.
1025
100
1590343737349015
Answer
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negative
positive
negative
positive
negative
positive
negative
positive
negative
positive
negative
positive
negative
positive
negative
positive
3 (4)
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10 2 3 4 5 6 7 8 9 1012345678910
To model on a number line:
You still start at 0.
Then you go to the first number.
5 (2)
Think of the minus sign as meaning do the opposite of the second number
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10 2 3 4 5 6 7 8 9 1012345678910
Model
8 ( 9)
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-5 - 3
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-3 - (-7) =
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Try these: Watch your signs!
1. 6 7
2. 7 15
3. 8 (3)
4. 10 (18)
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Homework
Worksheet on 2.4 and 2.5
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2.4 and 2.5 answers
1. 12
2. 5
3. 11
4. 5
5. .2
6. 1
7. 4
8. 6
9. 1
10. 2
11. 8
12. 11
13. 5
14. 2
15. 7
16. 1
17. 1
18. 2
19. 4
20. 10