\(z^4-4z^3+17z^2-16z+52=0\)
\(z_1=2i\) → \(z_2=-2i\)
\((z^4-4z^3+17z^2-16z+52):[(z-2i)(z+2i)\\=(z^4-4z^3+17z^2-16z+52):[z^2-4i^2]\\=(z^4-4z^3+17z^2-16z+52):[z^2+4]\)
Polynomdivision
\((z^4-4z^3+17z^2-16z+52):(z^2+4)=z^2-4z+13\)
\(-(z^4+4z^2)\)
.........................
\(-4z^3+13z^2-16z+52\)
\(-(-4z^3-16z)\)
..................................
\(13z^2+52\)
\(-(13z^2+52)\)
..............................................
\(0\)
\(z^2-4z+13=0\)
\(z^2-4z=-13\)
\(z^2-4z+(\frac{4}{2})^2=-13+(\frac{4}{2})^2\)
\((z-2)^2=-13+4=-9=9i^2|±\sqrt{~~}\)
\(1.)\)
\(z-2=3i\)
\(z_3=2+3i\)
\(2.)\)
\(z-2=-3i\)
\(z_4=2-3i\)