Answer:
graphs 1, 2, 3, and 4, can represent a function
graphs 5 and 6 can not represent a function.
Explanation:
If for a given graph of a relationship you can draw a vertical line that intersects the graph in more than one point, then we can conclude that the graph does not represent a function.
Now, if we look at the first four graphs, we can see that no vertical line intersects more than one point, so the first four can represent functions.
The special case here is graph number 2, where we can see a white dot right below a colored dot, and if we draw a vertical line there, the line will touch both points. But, a white dot means that the exact point does not belong to the graph, so if the line passes through there, it will not intersect the graph.
For the last two, this is not the case, in graph 5 and graph 6 we could draw vertical lines that intersect the graphs twice
(any line like x = n, with n < 0, intersects two points in graph 5, while the line x = 0 intersects twice the graph number 6)
So graph 5 and graph 6 can't represent functions.