Question

Factor z^3 - 2z^2 + 9z - 18

Answer 1

z³ - 2z² + 9z - 18=z²(z-2)+9(z-2)=(z-2)(z²+9).

Answer 2

$z^3 - 2z^2 + 9z - 18 = (z^3 - 2z^2 )(+ 9z - 18 )=z^2 (z-2)+9 (z-2) \\ \\ =\boxed {\bf {(z^2+9)(z-2)=(z-3i)(z+3i)(z-2)}}$