√(z²-4z+4)+√(z²+8z+16)=√(z-2)²+√(z+4)²=
=Iz-2I +I z+4I, z∈[-4,2]
--------------(-4)----------------2--------------------------
- - +
------------------/----------/-----2--------------------------
(z-2)<0 (z-2)>0
- +
---------------(-4)--/-------/------------------------------
z+4<0 z+4>0
т.о.Iz-2I +I z+4I= -(z-2)+(z+4)=6, z∈[-4,2]