The domain and range are defined for a relation and they are the sets of all the x-coordinates and all the y-coordinates of ordered pairs respectively. For example, if the relation is, R = {(1, 2), (2, 2), (3, 3), (4, 3)}, then: Domain = the set of all x-coordinates = {1, 2, 3, 4} Range = the set of all y-coordinates = {2, 3} take a look at the picture e.g Here, the domain is the set {A,B,C,E} { A , B , C , E } . D D is not in the domain, since the function is not defined for D D .
The range is the set {1,3,4} { 1 , 3 , 4 } . 2 2 is not in the range, since there is no letter in the domain that gets mapped to 2 2 .
