Take a positive value as a start. Then, take the result you get in the same formula again and again until you get consistent results.
For example, take the first as x = 1.5
Use this again,
Again and again, until you get 1.999 which is enough to say that x = 2
EDIT: There was a LaTeX error which took me some time to spot... and before I knew it, Ackbeet posted the link...