I just need a walkthrough or step by step process on how to get it so i can understand :)

Look at the following graph of the given equation. determine whether the equation is a function. explain why or why not.

How to do this , and can some one explain

Aplane intersects a pris paralel to the base of the prism. the cross section is a polygon wth eight sides. how many sides does the base of the prism have? a. 10 b. 8 c. 7 d. 9