Answer: A good way to determine if a line represents a valid function is to use the vertical line test.
To do this, you imagine a vertical (up and down) line moving across your graph from left to right. It should only be touching the line at one point at a time.
If it is touching more than one point on the line at a time, the line is not a valid function.
The first line and its inverse both pass the test.
The second line passes the test, but its inverse does not.
The third line also passes the test, but again, its inverse does not.
The same applies to the fourth line and its inverse.
Step-by-step explanation:
