SOLUTION: Which graph shows a function whose inverse is also a function? How do I choose the right one from a picture of graphs?

Question 1039163: Which graph shows a function whose inverse is also a function?
How do I choose the right one from a picture of graphs?
Answer by Edwin McCravy(20054) (Show Source): You can put this solution on YOUR website!

In general,
A function graph must not pass above or below itself.
Therefore, for its inverse to be a function, it must not 
pass either to the right or left of itself. 

Or ---

A function graph must pass the vertical line test.  That is,
no vertical line can intersect the graph more than once.  
Therefore, in order for a function to have an inverse which 
is also a function, its graph must pass the horizontal line 
test.  That is, no horizontal line can intersect the graph 
more than once.

Edwin

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