do now. 2/5/2015 7-3b integers and absolute value
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Do Now
2/5/2015 7-3B Integers and Absolute Value
positive integer- greater than 0
-may be written with a positive sign (+), but they are usually written w/o it
negative integer- less than 0.
-ALWAYS written with a negative sign (–)
Example 1Write an integer for 100 feet below sea level.
Because it represents below, the integer is −100.
travel.nationalgeographic.com
Example 2Write an integer for winning 3 tickets.
Because it represents winning, the integer is 3. epay.newschool.edu
Ex. 3
Write an integer for a gain of ten yards.
www.nytimes.com
Gain is an increase of 10
Ex. 4
Write an integer for a penalty of fifteen yards.
www.nytimes.com
Penalty is an loss or decrease -15
Example 5
A jet climbing to an altitude of 20,000 feet
Positive numbers can represent climbing or rising.
20,000
Ex. 6
You are taking $15 out of your savings account
Negative numbers can represent taking out or withdrawing. -15
$
Example 7
7 degrees below zero
Negative numbers can represent values below or less than a certain value. -7
Example 8Graph the set of integers {–3, 1, 0} on a number line.
Draw a number line.
Then draw a dot at the location of each integer.
The set of whole numbers includes zero and the counting numbers.
{0, 1, 2, 3, 4, …}
Remember!
absolute value- its distance from 0 on a # line
- The symbol ||
–5 –4 –3 –2 –1 0 +1 +2 +3 +4 +5
|–3| = 3 |3| = 3
|<--3 units--> | <--3 units-->|
• Absolute values are NEVER negative.
• Opposite integers have the same absolute value.
• |0| = 0
Example 9
Use a number line to find the absolute value of each integer.
|–2|
–2 is 2 units from 0, so |–2| = 2
2
–5 –4 –3 –2 –1 0 +1 +2 +3 +4 +5
Example 10
|8|
8 is 8 units from 0, so |8| = 8
8
–1 0 1 2 3 4 5 6 7 8 9
Example 11Evaluate the expression |18|.
So, |18| = 18.
Example 12Evaluate |11| – |–9 |.
|11| − |−9| = 11 − |−9| The absolute value of 11 is 11.
= 11 − 9 or 2 The absolute value of −9 is 9.
Name a positive or negative integer represent each situation.
1. earned $15
2. 12 feet below sea level
3. What is the opposite of –6?Find and graph the absolute value of each integer.
4. -|–7| 5. |4| - |-3|
–12
+15
6
-7 1
Exit Ticket
Homework
• Pg. 421 #1-40 Evens