Notes, Lesson P.1
Real Numbers and their Properties
Course Notes Course Home Page Sample Problems for this Lesson
Sets of Numbers | Diagram of Relationships of Sets | Absolute Value | Order of Operations
Properties | Properties of Equality | The Equal Rights Amendment for Algebra
Sets of NumbersTop of this Page
Set a collection of items or objects.
Elements the individual items or objects that are in sets
Union the joining of sets into a master set. Union will not yield multiples of the same item
Intersection what is common between two sets
Null Set a set with no contents 
Subset a set, all of whose elements are also elements of the other set
Sets of Numbers we will be studying:
Number Set
Letter
Definition
Examples
Natural Numbers
(Counting)
N
{1,2,3,...}
Whole Numbers
W
{0,1,2,...}
Integers
IN
{...,-1,0,1,...}
Rational Numbers
Q
Irrational Numbers
IR
Real Numbers
R
Any of the above
Imaginary Numbers
IM
Square roots of negative numbers. By definition, 
i,-3i,19i
Complex Numbers
C
18i, 14+7i, 8
Rational Numbers in Decimal Form: repeater or terminator

Irrational Numbers in Decimal Form: non-repeating, non-terminating

Diagram of Relationships of SetsTop of this Page

The number line is not filled until all of R is included. That is why it is called the Real Number Line.
 

Q is used here because R is reserved for Real Numbers. Q is a logical replacement however. It stands for Quotient, which is at the heart of the Definition of the Rational Numbers.


Absolute ValueTop of this Page

Definition:

Absolute Value The distance that a number is from zero on the number line. This must always be either zero or positive.
Using the above definition, if we were told that the distance from an object is x units, it means that we are either x units to the left of the goal, or x units to the right of the goal.
Troubling Statement:
Remember:
The "-" sign in front of a number or variable really does not mean "negative," it means additive inverse. Of course the additive inverse of a number can be positive. And so, the absolute value of an expression can have a "-" sign in it.
With Absolute value, what we have is an ambidextrous statement. As the "troubling statement" above points out, there are two possible solution to an absolute value statement. Therefore, we will have to find two solutions to these problems, before we can find a combined, final solution.
Order of Operations Top of this Page
Definitions:
 
Order of Operations The order in which  mathematical operations must be done. 
 
Abbr..
Memory
Represents
Rank
P
Please
Parentheses
1
E
Excuse
Exponents
2
M
My
Multiplication
3
D
Dear
Division
3
A
Aunt
Addition
5
S
Sally
Subtraction
5
In case of a tie, work from left to right.
Expression A mathematical statement using numbers, variables, and operations.
Algebraic Expression An expression which has at least one variable in it.
Formula A mathematical sentence that expresses the relationship between certain quantities. 

Example: A ball has a radius of 8.3 in. Find the surface area of the ball.   A: area; r: radius 

Properties:Top of this Page

Property
Addition
Multiplication
Commutative property
Associative property
Distributive property
Identity Property
Inverse Property
Substitution property if  then either can be substituted for either at any time
Closure property If two elements of a set can be combined using an operation and a third number from that same set always results The set of integers is closed under subtraction because when you subtract 2 integers, it will always result in an integer
Equal Rights Amendment for Algebra (ERAA) Whatever you do to one side of an equation, you must do the same to the other side also.
Properties of EqualityTop of this Page
Reflexive Property For any real number a, a = a
Symmetric Property For all real numbers a and b, if a = b, then b = a
Transitive Property For all real numbers a, b, and c, if a = b and b = c, then a = c.
The Equal Rights Amendment for AlgebraTop of this Page
Property Definition Example Notes
Equal Rights Amendment for Algebra (ERA) Whatever you do to one side of an equation, you must do the same to the other side also
Subtraced 3 from both sides
Equal Rights Amendment for Algebra (ERA) Whatever you do to one side of an equation, you must do the same to the other side also
Divided both sides by 14
Equal Rights Amendment for Algebra (ERA) Whatever you do to one side of an equation, you must do the same to the other side also
Multiplied both sides by 3
Equal Rights Amendment for Algebra (ERA) Whatever you do to one side of an equation, you must do the same to the other side also
Took both square roots of both sides
Equal Rights Amendment for Algebra (ERA) Whatever you do to one side of an equation, you must do the same to the other side also
Squared both sides

Top of this PageCourse Page