Q. If $i\mathcal{z}^{3} + \mathcal{z}^{2}\mathcal{- z +}i = 0$, then $\mathcal{|z|}$ is equal to

A) 1
B) $i$
C) $- 1$
D) $- i$
Explanation

(a)
$\mathcal{z}^{3} + \frac{1}{i}\mathcal{z}^{2} - \frac{\mathcal{z}}{i} + 1 = 0$
$\Rightarrow \ \ \mathcal{z}^{3} - i\mathcal{z}^{2} + i\mathcal{z} + 1 = 0$
$\Rightarrow \ \ \mathcal{z}^{2}\left( \mathcal{z -}i \right) + i\left( \mathcal{z -}i \right) = 0$
$\Rightarrow \ \ \left( \mathcal{z -}i \right)\left( \mathcal{z}^{2} + i \right)\ \ \Rightarrow \ \left| \mathcal{z} \right| = 1$

Dr. Abubacker
Reviewed by Dr. Abubacker

Physics Educator & NEET/JEE Specialist

Ph.D. in Physics with 19+ years of teaching experience.