p(2i)=0
(z^4 + z^3 + 3z^2 + 4z − 4):(z^2 + 4)=z^2 + z - 1
z^4 +4z^2
-------------------------
z^3 - z^2
z^3 +4z
------------------------
-z^2 - 4
-z^2 - 4
----------------------
0
reelle Zerlegung (z^2+4)(z+0,5+√(5/4))(z-0,5+√(5/4))
komplex (z-2i) (z+2i)(z+0,5+√(5/4))(z-0,5+√(5/4))