Question

Write the following relations as sets of ordered pairs and find which of them are functions :
(i) {(x,y):y=3x,xϵ(1,2,3),yϵ(3,6,9,12)}
(ii) {(x,y):y>x+1,x=1,2} and y = 2, 4, 6
(iii) {(x,y):x+y=3,x,yϵ{0,1,2,3}}