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TS EAMCET · Maths · Complex Number

The number of common roots among the \(12^{\text {th }}\) and \(30^{\text {th }}\) roots of unity is

  1. A 12
  2. B 9
  3. C 8
  4. D 6
Verified Solution

Answer & Solution

Correct Answer

(D) 6

Step-by-step Solution

Detailed explanation

We know that \(n^{\text {th }}\) roots of unity \(=e^{\frac{i 2 K \pi}{n}}\) \(\therefore 12^{\text {th }}\) roots of unity is \(e^{i \frac{2 K \pi}{12}}=e^{i \frac{K \pi}{6}}\) \(30^{\text {th }}\) roots of unity is \(e^{i \frac{2 K \pi}{30}}=e^{i \frac{K \pi}{15}}\) Common…