Theoreticals of Calculus: I have the solutions posted in the pdf attachment, could someone help me understand the first problem asking to Find the interior of each set.

Question

anonymous · Answer

The interior is just the epsilon neighborhoods with the boundaries stripped off, right?
We can do this.

anonymous · Answer

oh ok, so for e) the int is empty set because there is no boundary other than 2 in that set?

anonymous · Answer

oh wait i forgot to attach the pdf

anonymous · Answer

It's an intersection, not a union.  The result of the intersection is the set of just 2.  This isn't an epsilon neighborhood, so there is no interior.

anonymous · Answer

oh ok thanks!