Bug with symbolic solve?

Richard Jackson wrote: May we call it a bug? . Is there something else we might call it?

Hmm, its PTC - maybe its a feature!? PTC marketing sure can make that possible.

Has anybody an explanation why the symbolic solve produces that many wrong solution if used without the modifer "fully"? Because there's a bug

Yes, and obviously "fully" makes the symbolics to think about its results a second time

Alan's explanation make it clear whats happening - false solutions coming from taking the equation to the power of 4.

I use others tools in some cases:

AlanStevens wrote: I think it's clear enough where the extra solutions come from; Mathcad must do something like the following on solving the equation.

Thank! Yes, at least with your explanation its clear what happens.

Nevertheless a bug which should not happen.

Also intersting the different behaviour when using the fourth root instead.

I know the difference between (-1)^(1/3) and the third root of -1 (only the latter is -1) but not sure about the fourth root and how the symbolics sees it.

Werner