# Homework Help: Prove a given limit using epsilon-delta

1. Oct 5, 2011

### Freye

1. The problem statement, all variables and given/known data

Suppose that A_n is, for each natural number n, some finite set of numbers in [0,1] and that A_n and A_m have no members in common if m=/n. Define f as follows:

f(x) = 1/n if x is in A_n
f(x) = 0 if x is not in A_n for any n

Prove that the limit of f(x) as x goes to a is zero for all a in [0,1]

2. Relevant equations
for every $\epsilon$ there exists a $\delta$ such that
0<|x-a|<$\delta$ : |f(x)-L|<$\epsilon$

3. The attempt at a solution

Well I'm not even really sure how to start this one so maybe someone could just give me a hint for what to choose as my epsilon and hopefully I can take it from there.