REAL NUMBERS

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# REAL NUMBERS - PowerPoint PPT Presentation

REAL NUMBERS. (as opposed to fake numbers?). Objective. TSW identify the parts of the Real Number System TSW define rational and irrational numbers TSW classify numbers as rational or irrational. Real Numbers. Real Numbers are every number.

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### REAL NUMBERS

(as opposed to fake numbers?)

Objective
• TSW identify the parts of the Real Number System
• TSW define rational and irrational numbers
• TSW classify numbers as rational or irrational
Real Numbers

Real Numbers are every number.

Therefore, any number that you can find on the number line.

Real Numbers have two categories.

What does it Mean?
• The number line goes on forever.
• Every point on the line is a REAL number.
• There are no gaps on the number line.
• Between the whole numbers and the fractions there are numbers that are decimals but they don’t terminate and are not recurring decimals. They go on forever.
Real Numbers

REAL NUMBERS

154,769,852,354

1.333

-5,632.1010101256849765…

-8

61

π

49%

549.23789

Two Kinds of Real Numbers
• Rational Numbers
• Irrational Numbers
Rational Numbers
• A rational number is a real number that can be written as a fraction.
• A rational number written in decimal form is terminating or repeating.
16

1/2

3.56

-8

1.3333…

- 3/4

Examples of Rational Numbers

### Integers

One of the subsets of rational numbers

What are integers?
• Integers are the whole numbers and their opposites.
• Examples of integers are

6

-12

0

186

-934

Types of Integers
• Natural Numbers(N): Natural Numbers are counting numbers from 1,2,3,4,5,................N = {1,2,3,4,5,................}
• Whole Numbers (W): Whole numbers are natural numbers including zero. They are 0,1,2,3,4,5,...............W = {0,1,2,3,4,5,..............} W = 0 + N

REAL NUMBERS

NATURAL

Numbers

WHOLE

Numbers

IRRATIONAL

Numbers

INTEGERS

RATIONAL

Numbers

Irrational Numbers
• An irrational number is a number that cannot be written as a fraction of two integers.
• Irrational numbers written as decimals are non-terminating and non-repeating.

Caution!

A repeating decimal may not appear to repeat on a calculator, because calculators show a finite number of digits.

Irrational numberscan be written only as decimals that do not terminate or repeat. They cannot be written as the quotient of two integers. If a whole number is not a perfect square, then its square root is an irrational number.

Try this!

a) Irrational

b) Irrational

c) Rational

d) Rational

e) Irrational

16 2

4 2

= = 2

Additional Example 1: Classifying Real Numbers

Write all classifications that apply to each number.

A.

5 is a whole number that is not a perfect square.

5

irrational, real

B.

–12.75

–12.75 is a terminating decimal.

rational, real

16 2

C.

whole, integer, rational, real

A fraction with a denominator of 0 is undefined because you cannot divide by zero. So it is not a number at all.

0 3

= 0

Additional Example 2: Determining the Classification of All Numbers

State if each number is rational, irrational, or not a real number.

A.

21

irrational

0 3

B.

rational

State if each number is rational, irrational, or not a real number.

4 0

C.

not a real number

Objective
• TSW compare rational and irrational numbers
• TSW order rational and irrational numbers on a number line
Comparing Rational and Irrational Numbers
• When comparing different forms of rational and irrational numbers, convert the numbers to the same form.

Compare -3 and -3.571

(convert -3 to -3.428571…

-3.428571… > -3.571

3

7

3

7

Ordering Rational and Irrational Numbers
• To order rational and irrational numbers, convert all of the numbers to the same form.
• You can also find the approximate locations of rational and irrational numbers on a number line.
Example
• Order these numbers from least to greatest.

¹/₄, 75%, .04, 10%, ⁹/₇

¹/₄ becomes 0.25

75% becomes 0.75

0.04 stays 0.04

10% becomes 0.10

⁹/₇ becomes 1.2857142…

Answer: 0.04, 10%, ¹/₄, 75%, ⁹/₇

Practice

Order these from least to greatest:

Objectives
• TSW identify the rules associated computing with integers.
• TSW compute with integers

1) (-4) + 8 =

### Examples: Use the number line if necessary.

4

2) (-1) + (-3) =

-4

3) 5 + (-7) =

-2

1) When the signs are the same,

ADD and keep the sign.

(-2) + (-4) = -6

2) When the signs are different,

SUBTRACT and use the sign of the larger number.

(-2) + 4 = 2

2 + (-4) = -2

Karaoke Time!

Addition Rule: Sung to the tune of “Row, row, row, your boat”

Same signs add and keep,different signs subtract,keep the sign of the higher number,then it will be exact!

Can your class do different rounds?

-3

Proof: 3 + (-3) = 0

We will use the additive inverses for subtraction problems.

Example: The additive inverse of 3 is

What’s the difference between7 - 3 and 7 + (-3) ?

7 - 3 = 4 and 7 + (-3) = 4

The only difference is that 7 - 3 is a subtraction problem and 7 + (-3) is an addition problem.

“SUBTRACTING IS THE SAME AS ADDING THE OPPOSITE.”

(Keep-change-change)

When subtracting, change the subtraction to adding the opposite (keep-change-change) and then follow your addition rule.

Example #1: - 4 - (-7)

- 4+ (+7)

Diff. Signs --> Subtract and use larger sign.

3

Example #2: - 3 - 7

- 3+ (-7)

Same Signs --> Add and keep the sign.

-10

Review

1) If the problem is addition, follow your addition rule.2) If the problem is subtraction, change subtraction to adding the opposite (keep-change-change) and then follow the addition rule.

State the rule for multiplying and dividing integers….

If the signs are the same,

If the signs are different,

the answer will be negative.

the answer will be positive.

Different

Signs

Negative

What’s

The

Rule?

1. -8 * 3

4. 6 ÷ (-3)

-24

-2

Start inside ( ) first

2. -2 * -61

5. - (20/-5)

122

- (-4)

Same

Signs

Positive

4

3. (-3)(6)(1)

(-18)(1)

6.

-18

Just take

Two at a time

68

7. At midnight the temperature is 8°C. If the temperature rises 4°C per hour, what is the temperature at 6 am?

How much

does the

temperature

rise each

hour?

How long

Is it from

Midnight

to 6 am?

+4 degrees

6 hours

(6 hours)(4 degrees per hour)

the original temp.

= 24 degrees

8° + 24° = 32°C

8. A deep-sea diver must move up or down in the water in short steps in order to avoid getting a physical condition called the bends. Suppose a diver moves up to the surface in five steps of 11 feet. Represent her total movements as a product of integers, and find the product.

Multiply

What

does

This

mean?

(11 feet)

(5 steps)

(55 feet)

5 * 11 = 55