For something to be considered to be a graph, every x value must have 1 y value. It does not matter if y values are the same, but you MUST make sure there is ONLY ONE of each value. So for example the second one wouldn't be a function because -5 appears twice for the x values, but with different y values. This would mean when graphed, it would fail the vertical line test (if you put a vertical line anywhere on the graph you will only get one point).
