Question

State wether the relations from A to B are functions : If A = {$2,4,6$} and B = {$a,9$), then R = { $(2,8),(2,9),(4,8),(4,9),(6,8)$ }. Type 1 if they are function and 0 if they are not

Answer 1

A function is a set of ordered pairs in which each $x$-element from the first set has only ONE $y$-element from the second Set associated with it.
Since elements $2,4$ of SET $A$ is associated with both $8,9$ of $B$, the given relation is not a function.