Question

Which of the following is not true?

• A. Every relation from the set A to the set B is a function from the set A to the set B.
• B. If f is a function from A to B and (a, b) Є f, then f(a) = b, where a is called the pre-image of b under f.
• C. Every function from the set A to the set B is a relation from the set A to the set B
• D. If f is a function from A to B and (a, b) Є f, then f(a) = b, where b is called the image of a under f.

Answer 1

The correct option is A

Every relation from the set A to the set B is a function from the set A to the set B.

A relation from the set A to set B is a function if:

(a) Each element of A is the first element of some ordered pair in the relation.

(b) No element of A is the first element of any two distinct ordered pairs in the relation.