Accedmychevron_right11thchevron_rightmathchevron_rightComplex Numberschevron_rightExercise 1.3

Question 5

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Solve the following equations .

(iii) 5z55z=05z^5 - 5z = 0

Solution

Factor out common factor 5z:5z(z41)=0Apply zero product property:5z=0    z=0z41=0    z4=1Difference of squares twice:(z21)(z2+1)=0z21=0    z2=1    z=±1z2+1=0    z2=1    z=±iTherefore: z=0,1,1,i,i\begin{aligned} & \boxed{\text{Factor out common factor 5z:}} \\ \\ & 5z(z^4 - 1) = 0 \\ \\ & \boxed{\text{Apply zero product property:}} \\ \\ & 5z = 0 \implies z = 0 \\ \\ & z^4 - 1 = 0 \implies z^4 = 1 \\ \\ & \boxed{\text{Difference of squares twice:}} \\ \\ & (z^2 - 1)(z^2 + 1) = 0 \\ \\ & z^2 - 1 = 0 \implies z^2 = 1 \implies z = \pm 1 \\ \\ & z^2 + 1 = 0 \implies z^2 = -1 \implies z = \pm i \\ \\ & \boxed{\text{Therefore: } z = 0, 1, -1, i, -i} \end{aligned}