Question

How do I tell if a relation is a function?

Answer 1

The same x cannot be paired with different y values. Given points (5,4) and (5,6) of a relation, the relation is not a function.

Answer 2

Thanks!

Answer 3

Unique image.

Answer 4

For my profile pic? Thanks! It's of Quasar, my favorite superhero.

Answer 5

An element of co-domain has unique f-image in domain.

\(f: A \to B \implies \) to each \(a \in A\) there exists a b\in B such that \((a,b) \in f \) and if \( (a_1,b_1) \in f \; and \; (a_1,b_2) \in f \implies b_1=b_2 \)