Let A = {1, 2, 4, 6, 7} and B = {5, 12, 7, 9, 8, 3}

Represent each of the following sets using complete listing method.

(a) D = {x: (x,y) ∈ R₁}
(b) D = {x: (x,y) ∈ R₂}
(c) R = {y: (x,y) ∈ R₁}
(d) R = {y: (x,y) ∈ R₂}

From your responses in Activity 2, observe that, in each case, the set represented by D contains all the first coordinates of the given relation and the set represented by R contains the second coordinates of the give relation.

In the above discussion the set of all the first coordinates of the ordered pairs of a relation R is called the domain of R and the set of all second coordinates of the ordered pairs of R is called the range of R.