Sets are collections of well-defined objects of the same kind. In our daily lives, we often talk about a collection of objects or groups of objects or numbers. For instance, a team of players, a collection of flowers, and a group of students.
Sets Notation
Mathematical, a set is often denoted or represented by a Capital letter. For example, F, G, A, B, Z, etc, and the members or elements of the set are enclosed in a curly bracket { }. So, if 4 is a member of set A, then we say A={4}.
Elements or Members of sets
Elements or members of sets are objects or components of a set. For example, B = {3,6,9,12,15}, then 3,12,6,15,9 are all elements or members of set B. i.e 3 ∈ B. Also all the elements in set ∈ B. In mathematics, the symbol ∈ “means belongs” to or is a “member of”.
We can also say that 5 ∉ B and 10 ∉ B. In mathematics, the symbol ∉ means “not belong to”
The number of elements or members in a particular set is denoted by n(A). For example A={1,3,5,7,9}. The number of elements in the set is n(A)=5.
Let’s look at some examples under sets
Example: if Q= {2,4,6,8,10,12,14,16,18,20} and B={1,3,5,7,9,11,13,15,17,19} complete the following statements by inserting ∈ or ∉.
a) 8…..Q
b) 5….B
c)11….Q
d)20…B
answer: a) 8 ∈ Q
b) 5 ∈ B
c) 11 ∉ Q
d) 20 ∉ B
For ways of describing a set click here