Applications of Negative Numbers
&Absolute Value
In
Algebra County
Zero
Down here, temperatures are negative.
Negative Numbers are found in
weather reports, but not in sunny
Florida!
There, the stock market went down.
Negative Numbers are found in stock market quotes
When losing
weight, the weight loss
is a negativenumber.
The number of feet below
sea level is a
negative number.
The number of feet below
sea level is a
negative number.
The number of feet below
sea level is a
negative number.
The number of feet below
sea level is a
negative number.
Checks are “subtracted” fromthe bank statement.
Negative Numbers are found
in banking.
Negative Numbers are found
in Jeopardy scores.
INALGEBRA COUNTY
ADDING INTEGERS
If it’s 70 degrees outside, and the temperature gets 10 degrees cooler, how can we write it?
70 10 60
If it’s -10 degrees outside, and the temperature goes down 10 degrees, how can we write it?
10 10 20
A positive added to a negative takes the sign of the largest “number.” We subtract.
If it’s 5 degrees outside, and the temperature gets 10 degrees colder, how can we write it?
5 10 5
A negative added to a negative is a “larger” negative. We add the “numbers.”
Another way to think of adding positive and negative numbers is by using red and yellow colored counters.
3 53 and -5 2
zero pairs
3 5 -3 and -5 8
No zero pairs
1. 18 20 22. 11 9 23. 6 5 114. 1 7 85. 2 9 76. 7 5 2
Write these in your notes pages
INALGEBRA COUNTY
MULTIPLYING INTEGERS
-5 TIMES 6CAN BE WRITTEN:
-5(6) -5 ·6(-5)(6)
2(3) MEANS:
•2 GROUPS OF 3
•A 2 BY 3 ARRAY
WE CAN PICTURE 2(3):
THESE AREALL ARRAYS
WE CAN PICTURE 2(3) AS 2 GROUPS OF 3:
Which?Group or array?
3 keys on
two key rings
A six-pack of cokesTwo rows of three
kitchen tiles
Two stacks of three books
The chairs
in church
When we multiply:
Positive X positive =Positive X negative =
Negative X positive =Negative X negative =
+-
-+
Don’t get confused:
Positive + positive =Positive + negative =
Negative + positive =Negative + negative =
+??
??-
Negative + positive =??
Why the question marks?
-4+6=2 (positive)
-6+4= -2 (negative)
Back to multiplication:
-(-3) means: - (-3)1
= 3Negative 1 times negative 3The number 1 is very
important in Algebra County.
Also: -(5) means:- (5) which
is:-5Negative 1 times
51
Let’s work some multiplication problems:
-2(5) -10=
3(-5) -15=
-4(-2) 8=
- (-6) 6=
-9(-11) 99=
- (-13) 13=
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