But in each case you have shown absolutely no effort on your part.
That is not the way this forum works.
This is not a homework service, they charge.
This is a free homework help service.
We help once you show some effort.
Pick an epsilon >0, then we have N such that .
You are home and dry if as the other terms are less than .
So lets increase N until we can minimise the first terms, note that for n>N we have 1/n<1/N, so we wish to find K such that for n>K
and a wise choice is where  denotes the next integer up.
Let then for n>M we have that
or some constant multiple.