How do I know if a graph represents a function
A graph represents a function if it passes the vertical line test.
The vertical line test is a method used to determine if a graph represents a function. If any vertical line intersects the graph at more than one point, then the graph does not represent a function.
In other words, if you can draw a vertical line that passes through the graph and touches it at only one point for every x-coordinate value, then the graph represents a function.