tgt

## Sunday, 24 March 2013

### Intermediate Algebra chapter 1

Sets and Other Basic Concepts
Chapter 1
Variables
A variable is a letter used to represent many numbers.
x, y, and z are usually used for variables.
Sometimes letters are also used to represent fixed constants (numbers that do not change).
a, b, c, and letters other than x, y, z are usually used for fixed constants.
In the formula ax = b, x is the variable while a and b are fixed constants.
Sets
A set is a collection of objects.
The objects are called elements or members.
The elements can be anything.
{ 1, 2, 3, 4, 5 } is a set of numbers.
{ dog, cat, mouse, dolphin } is a set of animals.
Sets are often assigned a capital letter for easy reference.
Examples:
A = { 2, 4, 6, 8, ... }
D = { ..., -4, -2, 0, 2, 4, ... }
Set Symbols
In roster form, the elements (or members) of a set are listed between braces: { ...elements... }
means "is an element of".
means "is not an element of".
Examples:
2    { 2, 4, 6, 8, ... }
-1    { ..., -4, -2, 0, 2, 4, ... }
Ø or { } means the empty set or null set, which is a set without elements.
means "is a subset of".
means "is not a subset of".
Subsets
A set, B, is a subset set of a set, C, if all the elements in B are also in C.
B    C is read "B is a subset of C."
A set, B, is not a subset set of a set, C, if one of the elements in B is not in C.
B    C is read "B is not a subset of C."
Sets of Numbers
Natural or CountingN{ 1, 2, 3, 4, ... }
WholeW{ 0, 1, 2, 3, 4, ... }
IntegerI{ ..., -1, -2, 0, 1, 2, ... }
RationalQFractions with the numerator
and denominator integers, and
the denominator is not 0;
repeating decimal numbers.
IrrationalHNumbers that are not rational
numbers, like  .
RealRAll numbers.

N    W    I    Q    R, andH    R
Set Builder Notation
Set builder notation is a way to express sets with out listing each element separately in roster form.

Set Builder NotationGraphical Representation
{ x |  x > a }
{ x |  x   a }
{ x |  a   x < b }
{ x |  a   x   b }
Union and Intersection of Sets
The union of two sets is a set containing all the elements from both sets.
The intersection of two sets is a set containing the elements common to both sets.
Symbols:
means "union".
means "intersection".
Relation Symbols
=  means "is equal to": the left-hand-side is equal to the right-hand-side.
means "is not equal to": the left-hand-side is not equal to the right-hand-side.
<  means "is less than": the left-hand-side is less than the right-hand-side.
means "is less than or equal to": the left-hand-side is less than or equal to the right-hand-side.
>  means "is greater than": the left-hand-side is greater than the right-hand-side.
means "is greater than or equal to": the left-hand-side is greater than or equal to the right-hand-side.