Question 188091
{(3,4),(-3,1),(4,4),(0,7)}
:
remember in a function there can be one and only one y value for each x value
in the other 3 there is two values of y for a given x......for instance 
in the 2nd grouping you have (0,4) and (0,7) so for x=0 you have y=4 and 7....