If $1, \omega, \omega^2$ are the cube roots of unity, then…

If $1, \omega, \omega^2$ are the cube roots of unity, then $(2-\omega)^2\left(2-\omega^2\right)^2\left(2-\omega^{10}\right)^2\left(2-\omega^{11}\right)^2=$
  1. $-7^4$
  2. $7^4$
  3. $7^8$
  4. $-7^8$

Solution

$1, \omega, \omega^2$ are the cube roots of units. $\Rightarrow 1+\omega+\omega^2=0$ Given, $(2-\omega)^2\left(2-\omega^2\right)^2\left(2-\omega^{10}\right)^2\left(2-\omega^{11}\right)^2$ $\begin{aligned} & =\left\{(2-\omega)\left(2-\omega^2\right)\right\}^2\left\{(2-\omega)\left(2-\omega^2\right)\right\}^2 \\ & =\left\{(2-\omega)\left(2-\omega^2\right)\right\}^4 \\ & =\left\{4-2\left(\omega+\omega^2\right)+\omega^3\right\}^4 \\ & =(4-2(-1)+1)^4=7^4\end{aligned}$

Asked in: AP EAMCET 2022 (07 Jul Shift 1)

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