Question

1). [(6,1), (6,2), (6,3)] 2). [(0,5), (5,-1), (5,9)] 3). [(1,-6), (3,-5), (1,0)] 4). [(0,8), (1,7), (2,6)]. Which of the following relations is a function?

Answer 1

Again, look for repeated entries in the domain.  If present, the relation cannot be a function.  1 maps 6 to 1, 2, and 3; 2 maps 5 to -1 and 9; 3 maps 1 to -6 and 0; and only 4 has no double mapping.  Therefore 4 is a function and the answer.