TN samacheer kalvi 10th Maths:
Chapter 1 Relations and Functions – Exercise 1.2 Introduction
1.
What are the Relations,
Domain, Co-Domain and Range?
A relation is a relationship between sets of values.
It is relation between x and y values of ordered pairs.
Let A and B be any two non-empty sets. A ‘Relation’ R from A to
B is a subset of AxB satisfying some specified conditions. If x ∈ A is related to y ∈ B through R , then we write it as x R y. x R
y if and only if (x,y) ∈ R .
The domain of the relation R ={x ∈ A | x R y, for some y ∈ B}
The co-domain of the relation R is B
The range of the relation R ={y ∈ B | xRy, for some x ∈ A}
2.
Representation of
Relation:
i.
A relation may be
represented algebraically either by the roster method or by the set builder
method.
ii.
An arrow diagram is a visual
representation of a relation.
3.
Important properties/Notes:
i.
If n(A) = p , n(B) =q ,then
the total number of relations that exist from A to B is 2pq
ii.
A relation which contains no
element is called a “null relation”.