Let A be a subset of the positive real. Prove that inf a = 0 <=> 0 is accmulation point of A

is it still true if A is the set of non negative reals? proof or give counter example

So I think I understand why this is true...since inf A=0 A is bounded below by 0, and we can have elements of A as close as we want to 0, but I dont know how to write it out?