91Ó°ÊÓ

For the first relation, $\left\{\right(2,5),(4,6),(6,7),(8,8\left)\right\}$there are no ordered pairs with the same first element and different second elements.

So the given relation is a function.

The domain is the set of first elements of ordered pairs and it is given as $\left\{2,4,6,8\right\}$.

The range is given by the set of second elements of ordered pairs and it is given as $\left\{5,6,7,8\right\}$.

The relation$\left\{(1,3),(4,-2),(-3,5),(1,7)\right\}$is not a function because there are two ordered pairs, $(1,3)$and $(1,7)$, that have the same first element and different second elements.

For the given graph, we draw a vertical line as

So it can be seen that a vertical line intersects the graph at more than one point. So the graph is not the graph of a function.

For the given graph, we draw a vertical line as

It can be seen that each vertical line intersects the graph at atmost one point.

So the given graph is the graph of a function.