We can use the vertical line test to check if each graph is a function. If the line passes through two points, it is not a function. If it only passes through one point then it is a function.
Graph 1:
It is a function because the line doesn't pass through more than one point. (yellow)
Graph 2:
It is not a function because the line does pass through more than one point. (orange)
Graph 3:
Horizontal lines are not functions. (orange)
Graph 4:
It is a function because the line doesn't pass through more than one point. (yellow)
Best of Luck!
