**Problem : **
For a given value of
*x*
and a
function
*f*
, how many values of
*f* (*x*)
exist?

**Problem : **
Is the graph below a graph of a function?

**Problem : **
Is the graph below a graph of a function?

**Problem : **
Is the graph below a graph of a function?

**Problem : **
Is the graph below a graph of a function?