1. it is not a function because the input 4 is going to two outputs.
2. it is a function because each x value is assigned to one y value.
3. it is not a function because the input 1,4 is shown two times.
4. it is a function because each x value is assigned to one y value.
5. and 6. they are both functions because each x value is assigned to one y value.
7. it is not a function because when doing the vertical line test, some lines are overlapping each other.
8. it is a function because when doing the vertical line test, no lines are overlapping each other.
If any of my answers are wrong, plz tell me and I will try and correct my mistake. Hope this helps!!