Math problem where graphing calculator may slow you down...

[Bunuel66]

Well, it seems that a fully analytical solution is rather trivial:

Using the variable transform u=ln(x) the problem reduces to tg(u)=1 whom solutions are:
u=pi/4+k.pi, k in Z.

Then searching u=ln(50) gives the upper bound which is for k=0. The following values are then for k=-1 and -2.

Same solution for degrees but then u=ln(1e20).

Nothing more than a pen, a 'small' paper and the first scientific calculator you can grasp around you (in that case a TI36X pro, shame on me ;-)