Download EX. (-5 + 6) + 2

Adding Real
Numbers (2.2)
Properties of Addition

Commutative Property – changing the
order of numbers being added does not
change the sum.
 EX.

3 + (-2) = (-2) + 3
Associative Property – Grouping does
not change the sum when adding.
 EX.
(-5 + 6) + 2 = -5 + (6 + 2)
Properties of Addition (cont.)

Identity Property – The sum of a number
and 0 is the number.
 EX.

-4+0=-4
Inverse Property – The sum of a number
and its opposite is zero.
 EX.
5 + (-5) = 0
What are Opposites?
•Two integers the same distance from the origin,
but on different sides of zero
•Every positive integer has a negative integer an
equal distance from the origin
•Example: The opposite of 6 is -6
•Example: The opposite of -2 is 2
Practice With Opposites
 Opposite
of -13
 Opposite
of 6
 Opposite
of -67
 Opposite
of 52
What is Absolute Value?
•Distance a number is from zero on a
number line (always a positive number)
•Indicated by two vertical lines | |
•Every number has an absolute value
•Opposites have the same absolute values
since they are the same distance from zero
•Example: |-8| = 8 and |8| = 8
•Example: |50| = 50 and |-50| = 50
Practice With Absolute Value
|12| =
|-95| =
|-17| =
|1/2| =
|10| =
|0| =
Adding Rules – Same Signs
•If the numbers have the SAME signs: ADD
the numbers & keep the same sign!
•Positive + Positive = Positive Answer
•Negative + Negative = Negative Answer
• Examples: -3 + (-10) = -13
•
6 + (8) = 14
Adding (Same Signs) - Examples
1)- 15 + (-12) =
2)-8 + (-9) + (-2) =
Adding (Same Signs) - Examples
3)
4)
(-3.5) + (-2) =
-2 + (-3.4) + (-2.1) =
Adding Rules – Different Signs
•If the numbers have the DIFFERENT signs:
SUBTRACT the numbers & use sign of the
BIGGER number!
•Bigger # is Positive = Positive Answer
•Bigger # is Negative = Negative Answer
• Examples: -13 + (7) = -6
•
23 + (-8) = 15
Adding (Different Signs) - Examples
1)25 + (-17)
2)4 + (-8) + 2
Adding (Different Signs) - Examples
3) (-18.5) + 12
4) (-9.2) + 10
Adding (Different Signs) - Examples
5) -4 + 10 + (-6)
6) 6.8 + 3.3 + (-4.1)
Notecard Check
1)
-10 + 12
2)
9 + (-1.7)
3)
1.5 + (-5.6) + 1
Homework
 Pg.
75
Numbers:
1, 11, 21 – 36.