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x / 0 Is undefined or indeterminant

Division by 0 is undefined or indeterminant.

Do not divide by 0.

Rational numbers have decimal representations that either terminate or do not terminate but contain a repeating block of digits. Some examples are:

3 4 = 0.75 Terminating 15 11 = 1.36363636 Nonterminating, but repeating

Some rational numbers are graphed below.

Graphs of rational numbers negative nine over two, negative five over three, negative one over eight, zero, two, and two and one fourth plotted on a number line.

Irrational numbers

The irrational numbers ( I r ) : Irrational numbers are numbers that cannot be written as the quotient of two integers. They are numbers whose decimal representations are nonterminating and nonrepeating. Some examples are

4.01001000100001 π = 3.1415927

Notice that the collections of rational numbers and irrational numbers have no numbers in common.

When graphed on the number line, the rational and irrational numbers account for every point on the number line. Thus each point on the number line has a coordinate that is either a rational or an irrational number.

In summary, we have

Sample set a

The summaray chart illustrates that

A rectangle labeled as Real numbers is divided into two parts, labeled as Rational numbers, and Irrational numbers, respectively. The part labeled as Rational number has three more rectangles placed one inside the other. These rectangles are labeled: the outermost as integers, the innermost as natural numbers, and the middle one as whole numbers. This illustrates that all real numbers are primarily classified as rational and irrational numbers.  And that all the natural numbers are whole numbers, all the whole numbers are integers, and all the integers are rational numbers. But the vice versa is not true.

Every natural number is a real number.

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Every whole number is a real number.

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No integer is an irrational number.

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Practice set a

Is every natural number a whole number?

yes

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Is every whole number an integer?

yes

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Is every integer a rational number?

yes

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Is every rational number a real number?

yes

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Is every integer a natural number?

no

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Is there an integer that is a natural number?

yes

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Ordering the real numbers

Ordering the real numbers

A real number b is said to be greater than a real number a , denoted b > a , if the graph of b is to the right of the graph of a on the number line.

Sample set b

As we would expect, 5 > 2 since 5 is to the right of 2 on the number line. Also, 2 > 5 since 2 is to the right of 5 on the number line.

Graphs of numbers negative five, negative two, five, and two plotted on a number line. The number line has arrows on each side, and is labeled from negative five to five in increments of one. The number line explains that negative two is greater than negative five, and five is greater than two.

Practice set b

Are all positive numbers greater than 0?

yes

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Are all positive numbers greater than all negative numbers?

yes

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Is 0 greater than all negative numbers?

yes

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Is there a largest positive number? Is there a smallest negative number?

no, no

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How many real numbers are there? How many real numbers are there between 0 and 1?

infinitely many, infinitely many

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Sample set c

What integers can replace x so that the following statement is true?

4 x < 2

This statement indicates that the number represented by x is between 4 and 2. Specifically, 4 is less than or equal to x , and at the same time, x is strictly less than 2. This statement is an example of a compound inequality.

Graphs of integers negative five to one plotted on a number line. The number line has arrows on each side, and is labeled from negative five to five in increments of one.

The integers are 4 , 3 , 2 , 1 , 0 , 1 .

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Draw a number line that extends from 3 to 7. Place points at all whole numbers between and including 2 and 6.

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Draw a number line that extends from 4 to 6 and place points at all real numbers greater than or equal to 3 but strictly less than 5.

Graphs of whole numbers between and including negative two and six plotted on a number line. The number line has arrows on each side, and is labeled from negative three to seven in increments of one. Negative two and negative one are not whole numbers, therefore they are not included in the graph.

It is customary to use a closed circle to indicate that a point is included in the graph and an open circle to indicate that a point is not included.

A number line with arrows on each end, and labeled from negative four to six in increments of one. There is a closed circle at three, and an open circle at five. These two circles are connected by a black line.

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Practice set c

What whole numbers can replace x so that the following statement is true?

3 x < 3

0, 1, 2

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Draw a number line that extends from 5 to 3 and place points at all numbers greater than or equal to 4 but strictly less than 2.

A horizontal line with arrows on both the ends.

A number line with arrows on each end, and labeled from negative five to three in increments of one. There is a closed circle at negative four and an open circle at two. These two circles are connected by a black line.

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Exercises

For the following problems, next to each real number, note all collections to which it belongs by writing N for natural numbers, W for whole numbers, Z for integers, Q for rational numbers, I r for irrational numbers, and R for real numbers. Some numbers may require more than one letter.

0

W , Z , Q , R

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For the following problems, draw a number line that extends from 3 to 3. Locate each real number on the number line by placing a point (closed circle) at its approximate location.

Is 0 a positive number, negative number, neither, or both?

neither

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An integer is an even integer if it can be divided by 2 without a remainder; otherwise the number is odd. Draw a number line that extends from 5 to 5 and place points at all negative even integers and at all positive odd integers.

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Draw a number line that extends from 5 to 5. Place points at all integers strictly greater than 3 but strictly less than 4.

A number line with arrows on each side, labeled from negative five to five in increments of one. The graphs of the integers negative two to three are plotted on the number line.

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For the following problems, draw a number line that extends from 5 to 5. Place points at all real numbers between and including each pair of numbers.

Draw a number line that extends from 5 to 5. Is it possible to locate any numbers that are strictly greater than 3 but also strictly less than 2 ?

A number line with arrows on each end, labeled from negative five to five, in increments of one. There are open circles at negative two and three with a dark shaded arrow to the left of negative two and right of three. ; no

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For the pairs of real numbers shown in the following problems, write the appropriate relation symbol ( < , > , = ) in place of the .

Is there a largest real number? If so, what is it?

no

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Is there a largest integer? If so, what is it?

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Is there a largest two-digit integer? If so, what is it?

99

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Is there a smallest integer? If so, what is it?

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Is there a smallest whole number? If so, what is it?

yes, 0

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For the following problems, what numbers can replace x so that the following statements are true?

1 x 5 x an integer

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7 < x < 1 , x an integer

6 , 5 , 4 , 3 , 2

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3 x 2 , x a natural number

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15 < x 1 , x a natural number

There are no natural numbers between −15 and −1.

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5 x < 5 , x a whole number

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The temperature in the desert today was ninety-five degrees. Represent this temperature by a rational number.

( 95 1 ) °

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The temperature today in Colorado Springs was eight degrees below zero. Represent this temperature with a real number.

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Is every integer a rational number?

Yes, every integer is a rational number.

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Is every rational number an integer?

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Can two rational numbers be added together to yield an integer? If so, give an example.

Yes. 1 2 + 1 2 = 1 or 1 + 1 = 2

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For the following problems, on the number line, how many units (intervals) are there between?

m and n , m > n ?

m n units

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a and b , b > a ?

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Exercises for review

( [link] ) Find the value of 6 + 3 ( 15 8 ) 4 .

23

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( [link] ) Find the value of 5 ( 8 6 ) + 3 ( 5 + 2 3 ) .

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( [link] ) Are the statements y < 4 and y 4 the same or different?

different

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( [link] ) Use algebraic notation to write the statement "six times a number is less than or equal to eleven."

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( [link] ) Is the statement 8 ( 15 3 4 ) 3 7 3 true or false?

true

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Questions & Answers

how did you get 1640
Noor Reply
If auger is pair are the roots of equation x2+5x-3=0
Peter Reply
Wayne and Dennis like to ride the bike path from Riverside Park to the beach. Dennis’s speed is seven miles per hour faster than Wayne’s speed, so it takes Wayne 2 hours to ride to the beach while it takes Dennis 1.5 hours for the ride. Find the speed of both bikers.
MATTHEW Reply
420
Sharon
from theory: distance [miles] = speed [mph] × time [hours] info #1 speed_Dennis × 1.5 = speed_Wayne × 2 => speed_Wayne = 0.75 × speed_Dennis (i) info #2 speed_Dennis = speed_Wayne + 7 [mph] (ii) use (i) in (ii) => [...] speed_Dennis = 28 mph speed_Wayne = 21 mph
George
Let W be Wayne's speed in miles per hour and D be Dennis's speed in miles per hour. We know that W + 7 = D and W * 2 = D * 1.5. Substituting the first equation into the second: W * 2 = (W + 7) * 1.5 W * 2 = W * 1.5 + 7 * 1.5 0.5 * W = 7 * 1.5 W = 7 * 3 or 21 W is 21 D = W + 7 D = 21 + 7 D = 28
Salma
Devon is 32 32​​ years older than his son, Milan. The sum of both their ages is 54 54​. Using the variables d d​ and m m​ to represent the ages of Devon and Milan, respectively, write a system of equations to describe this situation. Enter the equations below, separated by a comma.
Aaron Reply
find product (-6m+6) ( 3m²+4m-3)
SIMRAN Reply
-42m²+60m-18
Salma
what is the solution
bill
how did you arrive at this answer?
bill
-24m+3+3mÁ^2
Susan
i really want to learn
Amira
I only got 42 the rest i don't know how to solve it. Please i need help from anyone to help me improve my solving mathematics please
Amira
Hw did u arrive to this answer.
Aphelele
hi
Bajemah
-6m(3mA²+4m-3)+6(3mA²+4m-3) =-18m²A²-24m²+18m+18mA²+24m-18 Rearrange like items -18m²A²-24m²+42m+18A²-18
Salma
complete the table of valuesfor each given equatio then graph. 1.x+2y=3
Jovelyn Reply
x=3-2y
Salma
y=x+3/2
Salma
Hi
Enock
given that (7x-5):(2+4x)=8:7find the value of x
Nandala
3x-12y=18
Kelvin
please why isn't that the 0is in ten thousand place
Grace Reply
please why is it that the 0is in the place of ten thousand
Grace
Send the example to me here and let me see
Stephen
A meditation garden is in the shape of a right triangle, with one leg 7 feet. The length of the hypotenuse is one more than the length of one of the other legs. Find the lengths of the hypotenuse and the other leg
Marry Reply
how far
Abubakar
cool u
Enock
state in which quadrant or on which axis each of the following angles given measure. in standard position would lie 89°
Abegail Reply
hello
BenJay
hi
Method
I am eliacin, I need your help in maths
Rood
how can I help
Sir
hmm can we speak here?
Amoon
however, may I ask you some questions about Algarba?
Amoon
hi
Enock
what the last part of the problem mean?
Roger
The Jones family took a 15 mile canoe ride down the Indian River in three hours. After lunch, the return trip back up the river took five hours. Find the rate, in mph, of the canoe in still water and the rate of the current.
cameron Reply
Shakir works at a computer store. His weekly pay will be either a fixed amount, $925, or $500 plus 12% of his total sales. How much should his total sales be for his variable pay option to exceed the fixed amount of $925.
mahnoor Reply
I'm guessing, but it's somewhere around $4335.00 I think
Lewis
12% of sales will need to exceed 925 - 500, or 425 to exceed fixed amount option. What amount of sales does that equal? 425 ÷ (12÷100) = 3541.67. So the answer is sales greater than 3541.67. Check: Sales = 3542 Commission 12%=425.04 Pay = 500 + 425.04 = 925.04. 925.04 > 925.00
Munster
difference between rational and irrational numbers
Arundhati Reply
When traveling to Great Britain, Bethany exchanged $602 US dollars into £515 British pounds. How many pounds did she receive for each US dollar?
Jakoiya Reply
how to reduced echelon form
Solomon Reply
Jazmine trained for 3 hours on Saturday. She ran 8 miles and then biked 24 miles. Her biking speed is 4 mph faster than her running speed. What is her running speed?
Zack Reply
d=r×t the equation would be 8/r+24/r+4=3 worked out
Sheirtina
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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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