UPDATE: I spent a few mins today using trial and error methods to try and solve your original, none of my itterative formulae worked. -.- I've got the answer to be around about... x = 2.228833103999. XD

But I'm sure I can get it a little more precise... My calculator was refusing to bother with that many deciamal places. But try that, it's around there... I'm going out to a gig now, I'll use a better method once I get back. =P