1) {(-7,5),(-7,1),(-10,3),(-4,3)} 3) {(2,0),(6,2),(6,-2)}
2) {(-6,5),(-3,2),(1,2),(6,5)} 4) {(0,3),(2,4),(0,6)}

Remember that in order to be a function, each x value can only have one y value associated with it.

Let's look at the first two points of #1: (-7,5) and (-7,1). Those two points have the same x value, but different y values. So you know right away that #1 is not a function.

Now can you spot the one that doesn't have repeated x values in it?