First slide
De-moivre's theorem
Question

Let 1, ω,ω2 be the cube roots of unity. The least possible degree of a polynomial with real coefficients having roots 2ω,(2+3ω),2+3ω2,2ωω2 is __________

Moderate
Solution

Roots are 2ω,(2+3ω),2+3ω2,2ωω2 2+3ω and 2+3ω2 are conjugate to each other.2ω is complex root, then other root must be2ω2 (as complex roots occur in conjugate pair) 2ωω2=2(1)=3 which is real.
Hence, least degree of the polynomial is 5.

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