Question 142863
See this --> http://www.algebra.com/cgi-bin/show-question-source.mpl?solution=102766

then look at the a) and b).

Does a have a single domain entry that has two range values (read is there an x that has more than one value for y?) Yes, x=2 yileds both -2 and 3. So a cannot be a function.

Does b have a single domain entry that has two range values (read is there an x that has more than one value for y?) No. there are two different values of x that yeild the same y (9 and 4 both yield pi). But that is fine.

So the answer is b)