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.