Relation or Function?

Topic:
Functions
The graph below can display 6 different relations. Choose a relation using the selectboxes. Then, drag the vertical line by the diamond to check each relation to see if it is a function. Make sure to only have one relation selected at a time. 1. Which relations are functions? 2. Can functions zig-zag up and down? Can they zig-zag left to right? 3. Can a function have the same y-value more than once? (Can more than one point have the same y-value in a function?) 4. Can a function have the same x-value more than once? (Can more than one point have the same x-value in a function?)