Is it possible to determine the holes of a rational function simply from looking at the graph? If you have ONLY a graph and no equation, can you determine the holes?
Well, it depends. If the graph was drawn out in such a way that the holes were indicated -- usually with an open circle at the point where the hole exists -- then yes. This would mostly apply to a graph that had been drawn by hand since, as far as I know, a standard graphing calculator will not indicate holes in the graph in any visual way. (Of course for a graphing calculator to display a graph, it needs an equation, so it is sort of a moot point.)