Real Analysis: Epsilon- Delta HELP NEEDED
I have a final on Friday and i'm still not sure about a lot of things for this class... Here's this question:
let f: D-->R and define I f I: D--> R by I f I (x) = I f(x) I
a) suppose that f: D-->R is continuous at cED. Prove using an epsilon-delta argument that I fI is continuous at c.
b) Prove that I f I is continuous at c it does not necessarily follow that f is continuous at c.
I am completely lost on this problem, my professor is horrible
the I f I like represents absolute value? that's what all the I's stand for in the problem. Anyone know how to start this problem?