Describe the graph of the equation x = 7. Is the equation a function?
vertical line; yes
vertical line; no
horizontal line; no
horizontal line; yes
The graph of the equation x = 7 is a vertical line passing through the point (7,0) on the x-axis. Each point on the line has an x-coordinate of 7 and can have any y-coordinate.
Because the line passes the vertical line test, it is not a function. This is because a vertical line can pass through more than one point with the same x-coordinate, violating the definition of a function where each input (x-value) can only have one output (y-value).