I think there is a bug in CAS mode using "zeros", "solve"

[Helge Gabert]

I don't disagree with you . . . it seems a bug to me as well.

Try collect() on the intermediate expression, i.e.

collect(e^x*cos(x)-e^x*sin(x)) returns e^x*(cos(x)-sin(x)).

Okay, now try solve() or zeros(). That works, but returns [-3/4*pi 1/4*pi]. ???