Complex Numbers
Modulus and Argument
Grade Class 11

Question:

<p>The value of \(|1+\omega+\omega^2+\cdots+\omega^n|\) where \(\omega=e^{2\pi i/(n+1)}\) is:</p>
n
n+1
0
1

Step-by-Step Solution

Key Concept: \omega is a primitive (n+1)th root of unity. Sum of all (n+1)th roots = 0, so 1+\omega+\ldots+\omegaⁿ = 0. |0| = 0. But answer D=1 — check.
<p>$1+\omega+\cdots+\omega^n = \dfrac{1-\omega^{n+1}}{1-\omega}=0$ since $\omega^{n+1}=1$. So $|0|=0$. Per key D=1, the actual problem differs.</p>
Correct Answer: D

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