Junior Cert: Maths Sets and Venn Diagrams
Z or Integers
{ ...-3, -2, -1, 0, 1, 2, 3...} - Whole positive AND negative numbers including 0.
R
Real numbers - the set of all rational and irrational numbers
SET
a well defined collection of objects or things
UNION
all elements which are in P OR Q
INTERSECTION
all elements which shared by both sets P AND set Q
ELEMENT
an object in a set, also called a member
MEMBER
an object in a set, also called an element
UNIVERSAL SET
the set of objects under consideration
W or Whole numbers
{ 0,1,2,3,4,5...} - Whole POSITIVE numbers including 0.
N or Natural numbers
{ 1,2,3,4,5...} - whole POSITIVE numbers > 0.
SUBSET
Every element of P is also an element of Q. For example if set Q = {1,2,3,4,5,6}, P ={2,4,6} and R ={2,4,6,8} then P is a subset of Q but R is not a subset of Q because 7 is not in Q
COMPLEMENT
the elements that are NOT in the stated set Example: A' is read ''complement of A'' and means all the elements that are NOT in A
VENN DIAGRAM
A rectangle represents the Universal Set the subsets within are it represented by circles
EMPTY SET
A set with no elements { }
Cardinal number of a set - n(S) or #
The cardinal numbers is the number of elements in a set if D= {2,3,4,5,6,7,8,9,} then the n(D)=8 or # = 8.
Q
The set of Rational numbers that can be written as a fraction where the numerator and the denominators are both integers and the denominator is NOT 0
A \ B
The set of elements that are in A but not shared with any elements in set B.