I need to find simple limit: $\lim_{n\to\infty}{\sqrt{n+1}-\sqrt{n}}$
I can't use L'Hôpital's rule, which I think is natural for such problems. How to calculate such limit using only basic methods (definition and simple transformations etc.)?
It's one problem (from 50 problems) I don't know how to solve from my homework.
Thanks for help.