How can we determine from a graph if a function is shown or not?
To determine if a function is shown on a graph or not, we can use the horizontal line test.
The horizontal line test states that for a given graph, if any horizontal line intersects the graph at more than one point, then the graph does not represent a function. However, if every horizontal line intersects the graph at most once, then the graph represents a function.
To apply this test, we trace a horizontal line (either mentally or physically) across the graph and observe each intersection point. If at any point the line intersects the graph in more than one place, then the graph does not represent a function. If, however, the line never intersects the graph in more than one place for any horizontal position, then the graph represents a function.