Let w = cos and α = w + w 2 + w 4 and β = w 3 + w 5 + w 6 . 2α equals :

Mathematics · JEE Advanced · NTA Exams — Complex Numbers and Quadratic Equations

Let w = cos and α = w + w² + w⁴ and
β = w³ + w⁵ + w⁶.
2α equals :

1. \(-1+\sqrt{7} i\)
2. \(-1-\sqrt{7} \mathrm{i}\)
3. 1 + 7i
4. 1 – 7i

Answer

(A) -1+ 7 i

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