Have a look at this irrational equation

http://theprof.altervista.org/eq.gif

Its domain is [1;+infty).

The main math packages (Derive, Maple and Mathematica) we have here, at school, give x = 0 and x = 2, both as solutions!

Actually if you square twice, at last you get:

x² - 2x = 0

that leads to x = 0 and x = 2, but x = 0 IMHO is not a solution...

What do you think about?

best regards