Calculus
posted by Jonah .
How can you tell where on a graph f is discontinuous? What are the criteria?

usually there will be a fraction involved. Wherever the denominator is zero, f(x) will be undefined.
Or there may be a square root or logarith. f(x) not defined when the radicand is negative.
In general, look for values where f(x) is not defined; it is discontinuous there. 
What if there isn't a fraction at all and it's just a graph with a function on it? My homework doesn't have a given expression of a function just a graphical representation of it.

If all you have is the graph, then if there are any vertical asymptotes or holes in the graph, that's where f(x) is discontinuous.
I mean, jeez. you must have an intuitive feel for what "continuous" means. Math usually tries to use words that already have meaning. 
Alright I was clarifying since it's going to be graded. Doesn't hurt, does it?