Question

For my practice review, I need help to determine if these are functions or not.

Answer 1

1: no

2: no

3: yes

4: no

5: yes

6: yes.

Explanation:

Think of a vertical line sweeping across the graph from left to right. If ever this line crosses two points of the graph at the same time, it cannot be a function, since a function can only have max. 1 result per x value.