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2/5/ B 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 1 Write an integer for 100 feet below sea level. Because it represents below, the integer is −100. travel.nationalgeographic.com

Example 2 Write 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. Gain is an increase of 10

Ex. 4 Write an integer for a penalty of fifteen yards. 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 8 Graph 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 – |–3| = 3 |3| = 3 | | | 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 –

Example 10 |8| 8 is 8 units from 0, so |8| = 8 8 –

Example 11 Evaluate the expression |18|. So, |18| = 18.

Example 12 Evaluate |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 $ 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| – Exit Ticket

Homework Pg. 421 #1-40 Evens