Thread:HMcCoy/@comment-28838092-20140825225626/@comment-24808864-20140826000725

On the third problem, you run into an example of something that does not has an infinite domain, but it is not all real numbers.

For example, the x-value of 0 can be used to make a point on the graph. Right? (0,3) or (0,-3). It can actually make two!

Can an x-coordinate of -6 represent a point of the graph? It sure can, what are the coordinates of the point with x-coordinate -6 that is on the graph.

But now consider the x-coordinate of -7. The graph does not extend further to the left than -6. It goes that far, and then start going back to the right. There are no points on the graph that have an x-coordinate of -7. So -7 is not in the domain.

What do you think the domain would be then? Where do x-coordinates start being allowed? How long are they allowed for (how high an x-coordinate can you use)? How about range? What y's are allowed?