If $\omega (\neq 1)$ be a cube root of unity and $(1 + \omega^2)^n = (1 + \omega^4)^n$, then the least positive value of $n$ is
A2
B3
C5
D6
Answer & Solution
Correct answer: B. 3
For a non-real cube root of unity, $\omega^3=1$ and $1+\omega+\omega^2=0$.
Also, $\omega^4=\omega$.
So the given condition becomes
$$
(1+\omega^2)^n=(1+\omega)^n
$$
Using $1+\omega=-\omega^2$ and $1+\omega^2=-\omega$, we get
$$
(-\omega)^n=(-\omega^2)^n
$$
Hence
$$
\omega^n=\omega^{2n}
$$
Therefore
$$
\omega^n(1-\omega^n)=0
$$
Since $\omega\neq 0$, this gives
$$
\omega^n=1
$$
Now $\omega$ is a cube root of unity different from $1$, so its order is $3$. Therefore the least positive $n$ is
$$
3
$$
Checking the options, this matches option $\text{B}$.
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