Final answer:
To determine if a relation is a function, use the vertical line test to check if there is only one y-value for every x-value.
Step-by-step explanation:
To determine if a relation is a function, you can test it using the vertical line test. The vertical line test states that for every x-value, there should only be one corresponding y-value. If a vertical line intersects the graph of the relation at more than one point, then it is not a function. Here's an example:
Let's say we have the ordered pairs (2, 4), (3, 6), (4, 8), (5, 10). We can plot these points on a graph, and if a vertical line intersects the graph at more than one point, then it is not a function. In this case, the points form a straight line, and no vertical line intersects it at more than one point, so it is a function.