Definition of Function
"A function f from a set A to a set B is a relation that assigns to each element x in the set A exactly one element y in the set B. The set A is the domain (or set of inputs) of the function f, and the set B contains the range (or set of outputs)."
See Set A and B below.
A = {(1, 9), (2, 13), (3, 15), (4, 15), (5, 12), (6, 10)}
I say Set A is a function because every x is assigned to exactly one y.
Yes?
B = {(1, 9), (2, 13), (3, 15), (2, 15), (5, 12), (6, 10)}
I say Set B is not a function because x = 2 is assigned to two different values of y.
Yes?
Do not discuss one-to-one functions here. I am not there in the textbook.
