Answer:
Step-by-step explanation:
A function maps each value of the independent variable to one value of the dependent variable. If an input maps to two or more different outputs, the relation is not a function.
On a graph, two or more different output values for the same input will show up as points vertically aligned with each other. That is, a vertical line will intersect the graph in more than one place. When that happens, we say the graph does not pass the vertical line test, so is not a function.
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On the graph of these points, we show the vertical line that intersects two of the points of the given relation. The relation fails the vertical line test.