If $\mathrm{w}=\frac{-1+\mathrm{i} \sqrt{3}}{2}$, where $\mathrm{i}=\sqrt{-1}$, then the value of…
If $\mathrm{w}=\frac{-1+\mathrm{i} \sqrt{3}}{2}$, where $\mathrm{i}=\sqrt{-1}$, then the value of $\left(3+w+3 w^2\right)^4$ is
- 16
- -16
- 16 w
- $16 w^2$
Solution
$\omega$ is a complex cube root of unity
$\begin{array}{ll}
\therefore \quad & \omega=1 ...(i)\\
\therefore \quad & 1+\omega+\omega^2=0, \\
\therefore \quad & \left(3+\omega+3 \omega^2\right)^4 ...(ii)\\
& =(3+\omega+3(-1-\omega))^4 \\
& =(3+\omega-3-3 \omega)^4 \\
& =(-2 \omega)^4 \\
& =16 \omega^4 \\
& =16 \omega^3 \times \omega \\
& =16 \omega
\end{array}$
...[from (ii)]
...[from (i)]
Asked in: MHT CET 2024 (10 May Shift 1)
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