Accedmychevron_right11thchevron_rightmathchevron_rightComplex Numberschevron_rightExercise 1.3

Question 2

auto_storiesAcademic Material

Factorize into linear factors.

(iii) z32z2+16z32z^3 - 2z^2 + 16z - 32

Solution

Group terms:(z32z2)+(16z32)=z2(z2)+16(z2)Factor out (z2):=(z2)(z2+16)Now factor z2+16=z2(4i)2:z2+16=(z4i)(z+4i)Therefore:z32z2+16z32=(z2)(z4i)(z+4i)\begin{aligned} & \boxed{\text{Group terms:}} \\ \\ & (z^3 - 2z^2) + (16z - 32) = z^2(z - 2) + 16(z - 2) \\ \\ & \boxed{\text{Factor out }(z - 2):} \\ \\ & = (z - 2)(z^2 + 16) \\ \\ & \boxed{\text{Now factor } z^2 + 16 = z^2 - (4i)^2:} \\ \\ & z^2 + 16 = (z - 4i)(z + 4i) \\ \\ & \boxed{\text{Therefore:}} \\ \\ & z^3 - 2z^2 + 16z - 32 = (z - 2)(z - 4i)(z + 4i) \end{aligned}