If $w=\frac{-1-i \sqrt{3}}{2}$ where $i=\sqrt{-1}$, then the value of $\left|\begin{array}{ccc}1 & w & w^2…

If $w=\frac{-1-i \sqrt{3}}{2}$ where $i=\sqrt{-1}$, then the value of $\left|\begin{array}{ccc}1 & w & w^2 \\ w & w^2 & 1 \\ w^2 & 1 & w\end{array}\right|$ is
  1. -1
  2. 0
  3. 1
  4. 3

Solution

$\begin{aligned} & \omega=\frac{-1-\mathrm{i} \sqrt{3}}{2}, \omega^2=\frac{1-3+2 \mathrm{i} \sqrt{3}}{4}=\frac{-1+\mathrm{i} \sqrt{3}}{2}, \\ & \omega^3=1, \omega^6=1 \\ & \left|\begin{array}{ccc}1 & \omega & \omega^2 \\ \omega & \omega^2 & 1 \\ \omega^2 & 1 & \omega\end{array}\right| \\ & =1\left(\omega^3-1\right)-\omega\left(\omega^2-\omega^2\right)+\omega^2\left(\omega-\omega^4\right) \\ & =1\left(\omega^3-1\right)+0+\omega^2\left(\omega-\omega^4\right) .\end{aligned}$ $\begin{aligned} & =\omega^3-1+\omega^3-\omega^6 \\ & =2 \omega^3-\omega^6-1 \\ & =2(1)-1-1 \\ & =0\end{aligned}$

Asked in: MHT CET 2024 (10 May Shift 2)

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