How can I get 2*(square root of n) to tend to the limit zero?

I need 2*(square root of n) to tend to the limit zero to prove another equation tends to the limit zero, allowed to multiply up etcetera, but cant seem to figure it out, any ideas welcome, also need to get (square root of (n+1)+square root of (n)) to tend to the limit zero for same other equation which is (square root of (n+1)-square root of (n)), this I know tends to the limit zero