By prove it what tools do you mean? By delta-epsilon defintion?

We can prove that if then

Proof: Consider an integerl . For

This implies that

Now you should know that if that ...so since this proves that ...take to acheive your limit.

Is that what you wanted? Or were you looking for something simpler?

Note: I think if you weren't looking for a proof like the one above you could just state that so