Answer:
1.) A function can't have any repeated x-coordinates
For example:
{(3, 4), (3, 6), (5, 4)}
This is not a function because 3 is repeated.
{(2, 1) (4, 1), (5, 1)}
This is a function because the y-coordinates can be the same, but not the x-coordinates.
2.) When a function is graphed, it will only have one intersection point with a vertical line.
For examples, see the image attached.
