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This module is from Elementary Algebra by Denny Burzynski and Wade Ellis, Jr. The basic operations with real numbers are presented in this chapter. The concept of absolute value is discussed both geometrically and symbolically. The geometric presentation offers a visual understanding of the meaning of |x|. The symbolic presentation includes a literal explanation of how to use the definition. Negative exponents are developed, using reciprocals and the rules of exponents the student has already learned. Scientific notation is also included, using unique and real-life examples.Objectives of this module: be familiar with positive and negative numbers and with the concept of opposites.

Overview

  • Positive and Negative Numbers
  • Opposites

Positive and negative numbers

When we studied the number line in Section [link] we noted that

Each point on the number line corresponds to a real number, and each real number is located at a unique point on the number line.

A number line with arrows on each end, labeled from negative six to six in increments of one. There are two closed circles at negative two and four, respectively.

Positive and negative numbers

Each real number has a sign inherently associated with it. A real number is said to be a positive number if it is located to the right of 0 on the number line. It is a negative number if it is located to the left of 0 on the number line.

The notation of signed numbers

A number is denoted as positive if it is directly preceded by a " + " sign or no sign at all.
A number is denoted as negative if it is directly preceded by a " " sign.

The " + " and " - " signs now have two meanings:

+ can denote the operation of addition or a positive number.
can denote the operation of subtraction or a negative number.

Read the "-" Sign as "negative"

To avoid any confusion between "sign" and "operation," it is preferable to read the sign of a number as "positive" or "negative."

Sample set a

8 should be read as "negative eight" rather than "minus eight."

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4 + ( 2 ) should be read as "four plus negative two" rather than "four plus minus two."

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6 + ( 3 ) should be read as "negative six plus negative three" rather than "minus six plusminus three."

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15 ( 6 ) should be read as "negative fifteen minus negative six" rather than "minus fifteenminus minus six."

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5 + 7 should be read as "negative five plus seven" rather than "minus five plus seven."

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0 2 should be read as "zero minus two."

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Practice set a

Write each expression in words.

7 + ( 4 )

seven plus negative four

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9 + 2

negative nine plus two

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16 ( + 8 )

negative sixteen minus positive eight

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1 ( 9 )

negative one minus negative nine

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0 + ( 7 )

zero plus negative seven

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Opposites

Opposites

On the number line, each real number has an image on the opposite side of 0. For this reason we say that each real number has an opposite. Opposites are the same distance from zero but have opposite signs.

The opposite of a real number is denoted by placing a negative sign directly in front of the number. Thus, if a is any real number, then a is its opposite. Notice that the letter a is a variable. Thus, " a " need not be positive, and " a " need not be negative.

If a is a real number, a is opposite a on the number line and a is opposite a on the number line.

Two number lines with arrows on each end. The first number line has three labels, zero at the center, negative a to the left of zero and a to the right of zero. Negative a and a are equidistant from zero. The second line has three labels, zero at the center, a to the left of zero and negative a to the right of zero. The points a and negative a are equidistant from zero.

( a ) is opposite a on the number line. This implies that ( a ) = a .

This property of opposites suggests the double-negative property for real numbers.

The double-negative property

If a is a real number, then
( a ) = a

Sample set b

If a = 3 , then a = 3 and ( a ) = ( 3 ) = 3 .

A number line with arrows on each end, labeled from negative three to three in increments of three. Negative three is labeled as negative a, and three is labeled as a. There is an additional label for three as the opposite of negative a.

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If a = 4 , then a = ( 4 ) = 4 and ( a ) = a = 4 .

A number line with arrows on each end, labeled from negative four to four in increments of three. Negative four is labeled as a, and four is labeled as negative a. There is an additional label for negative four as the opposite of negative a.

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Practice set b

Find the opposite of each real number.

( 1 )

1 , since ( 1 ) = 1

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Suppose that a is a positive number. What type of number is a ?

If a is positive, a is negative.

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Suppose that a is a negative number. What type of number is a ?

If a is negative, a is positive.

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Suppose we do not know the sign of the number m . Can we say that m is positive, negative, or that we do notknow ?

We must say that we do not know.

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Exercises

A number is denoted as positive if it is directly preceded by ____________________ .

a plus sign or no sign at all

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A number is denoted as negative if it is directly preceded by ____________________ .

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For the following problems, how should the real numbers be read ? (Write in words.)

( 4 )

negative negative four

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For the following problems, write the expressions in words.

11 + ( 2 )

eleven plus negative two

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6 ( 8 )

six minus negative eight

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Rewrite the following problems in a simpler form.

( 8 )

( 8 ) = 8

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[ ( 3 ) ]

3

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[ ( 6 ) ]

6

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{ [ ( 26 ) ] }

26

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{ [ ( 11 ) ] }

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{ [ ( 31 ) ] }

31

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{ [ ( 14 ) ] }

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5 ( 2 )

5 ( 2 ) = 5 + 2 = 7

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6 ( 3 ) ( 4 )

13

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2 ( 1 ) ( 8 )

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15 ( 6 ) ( 5 )

26

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24 ( 8 ) ( 13 )

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Exercises for review

( [link] ) There is only one real number for which ( 5 a ) 2 = 5 a 2 . What is the number?

0

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( [link] ) Simplify ( 3 x y ) ( 2 x 2 y 3 ) ( 4 x 2 y 4 ) .

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( [link] ) Simplify x n + 3 x 5 .

x n + 8

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( [link] ) Simplify ( a 3 b 2 c 4 ) 4 .

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( [link] ) Simplify ( 4 a 2 b 3 x y 3 ) 2 .

16 a 4 b 2 9 x 2 y 6

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Questions & Answers

Three charges q_{1}=+3\mu C, q_{2}=+6\mu C and q_{3}=+8\mu C are located at (2,0)m (0,0)m and (0,3) coordinates respectively. Find the magnitude and direction acted upon q_{2} by the two other charges.Draw the correct graphical illustration of the problem above showing the direction of all forces.
Kate Reply
To solve this problem, we need to first find the net force acting on charge q_{2}. The magnitude of the force exerted by q_{1} on q_{2} is given by F=\frac{kq_{1}q_{2}}{r^{2}} where k is the Coulomb constant, q_{1} and q_{2} are the charges of the particles, and r is the distance between them.
Muhammed
What is the direction and net electric force on q_{1}= 5µC located at (0,4)r due to charges q_{2}=7mu located at (0,0)m and q_{3}=3\mu C located at (4,0)m?
Kate Reply
what is the change in momentum of a body?
Eunice Reply
what is a capacitor?
Raymond Reply
Capacitor is a separation of opposite charges using an insulator of very small dimension between them. Capacitor is used for allowing an AC (alternating current) to pass while a DC (direct current) is blocked.
Gautam
A motor travelling at 72km/m on sighting a stop sign applying the breaks such that under constant deaccelerate in the meters of 50 metres what is the magnitude of the accelerate
Maria Reply
please solve
Sharon
8m/s²
Aishat
What is Thermodynamics
Muordit
velocity can be 72 km/h in question. 72 km/h=20 m/s, v^2=2.a.x , 20^2=2.a.50, a=4 m/s^2.
Mehmet
A boat travels due east at a speed of 40meter per seconds across a river flowing due south at 30meter per seconds. what is the resultant speed of the boat
Saheed Reply
50 m/s due south east
Someone
which has a higher temperature, 1cup of boiling water or 1teapot of boiling water which can transfer more heat 1cup of boiling water or 1 teapot of boiling water explain your . answer
Ramon Reply
I believe temperature being an intensive property does not change for any amount of boiling water whereas heat being an extensive property changes with amount/size of the system.
Someone
Scratch that
Someone
temperature for any amount of water to boil at ntp is 100⁰C (it is a state function and and intensive property) and it depends both will give same amount of heat because the surface available for heat transfer is greater in case of the kettle as well as the heat stored in it but if you talk.....
Someone
about the amount of heat stored in the system then in that case since the mass of water in the kettle is greater so more energy is required to raise the temperature b/c more molecules of water are present in the kettle
Someone
definitely of physics
Haryormhidey Reply
how many start and codon
Esrael Reply
what is field
Felix Reply
physics, biology and chemistry this is my Field
ALIYU
field is a region of space under the influence of some physical properties
Collete
what is ogarnic chemistry
WISDOM Reply
determine the slope giving that 3y+ 2x-14=0
WISDOM
Another formula for Acceleration
Belty Reply
a=v/t. a=f/m a
IHUMA
innocent
Adah
pratica A on solution of hydro chloric acid,B is a solution containing 0.5000 mole ofsodium chlorid per dm³,put A in the burret and titrate 20.00 or 25.00cm³ portion of B using melting orange as the indicator. record the deside of your burret tabulate the burret reading and calculate the average volume of acid used?
Nassze Reply
how do lnternal energy measures
Esrael
Two bodies attract each other electrically. Do they both have to be charged? Answer the same question if the bodies repel one another.
JALLAH Reply
No. According to Isac Newtons law. this two bodies maybe you and the wall beside you. Attracting depends on the mass och each body and distance between them.
Dlovan
Are you really asking if two bodies have to be charged to be influenced by Coulombs Law?
Robert
like charges repel while unlike charges atttact
Raymond
What is specific heat capacity
Destiny Reply
Specific heat capacity is a measure of the amount of energy required to raise the temperature of a substance by one degree Celsius (or Kelvin). It is measured in Joules per kilogram per degree Celsius (J/kg°C).
AI-Robot
specific heat capacity is the amount of energy needed to raise the temperature of a substance by one degree Celsius or kelvin
ROKEEB
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Source:  OpenStax, Elementary algebra. OpenStax CNX. May 08, 2009 Download for free at http://cnx.org/content/col10614/1.3
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