Thanks for the info. BTW, Maple 9 stays unimpressed by any assumption to w (>0,<0,real,constant) and pops up the zero. Also the int-option continuous shows no effect. But setting w:= 1; works fine, for example, but isn't the common solution I was looking for. It's a bit disappointing that modern Maple versions lost the ability to handle such a simple equation, to be honest. Do I have to report this bug elsewhere for the Maple developers? Klaus