Question

For each relation, decide whether or not it is a function.

Answer 1

Relation 1: FUNCTION

Relation 2: NOT a function

Relation 3: FUNCTION

Relation 4: NOT a function

Relation 2 is not because if you are asked, "What is the output for 3?", there are two answers: 4 and 9.

To be a function, there can only be a single answer to that question.

Relation 4 is not because if you are asked, "What is the output for -2?", there are three answers: v, a and u.

Answer 2

Relation 1 is function. Relation 2 is function. Relation 3 is function. Relation 4 is not a function.