Page 139 - Basic College Mathematics with Early Integers

2.2 INTRODUCTION TO INTEGERS
Objectives

Represent Real-Life Situations
with Integers.
Objective Representing Real-Life Situations
Graph Integers
on a Number Line. Thus far in this text, all numbers have been 0 or greater than 0. Numbers greater
than 0 are called positive numbers. However, sometimes situations exist that cannot
Compare Integers. be represented by a number greater than 0. For example,
Find the Absolute Value of
a Number.
Find the Opposite of a Number.

Read Bar Graphs Containing
Integers. Sea level
0
5 degrees
below 0
20 feet below
sea level

To represent these situations, we need numbers less than 0.
Extending the number line to the left of 0 allows us to picture negative numbers,
which are numbers that are less than 0.

Negative Zero Positive
numbers numbers

5 4 3 2 1 0 1 2 3 4 5

When a single + sign or no sign is in front of a number, the number is a positive num-
ber. When a single - sign is in front of a number, the number is a negative number.
Together, we call positive numbers, negative numbers, and zero the signed numbers.
-5 indicates “negative five.”
5 and +5 both indicate “positive five.”
Notice that 0 is The number 0 is neither positive nor negative.
neither positive nor negative.
Some signed numbers are integers. The integers consist of the numbers labeled
on the number line above.The integers are

Á , -3, -2, -1, 0, 1, 2, 3, Á
Now we have numbers to represent the situations previously mentioned.

5 degrees below 0 -5°
20 feet below sea level -20 feet

Copyright 2012 Pearson Education, Inc.
A - sign, such as the one in -1, tells us that the number is to the left of 0 on a
number line. -1 is read “negative one.”
A + sign or no sign tells us that a number lies to the right of 0 on a number
line. For example, 3 and +3 both mean “positive three.”

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