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MathsMediumNumerical2021 · 26 Aug Shift 1

Q82.Let z = 1−i√32 , i = √−1. Then the value of 21 + (z + 1z ) 3 + (z2 + z21 ) 3 + (z3 + z31 ) 3 + … + (z21 + z211 ) 3 is______.

What This Question Tests

This problem involves recognizing a complex number as a cube root of unity, using its properties (especially z + 1/z), and summing a series of cubic terms based on powers of this complex number.

Concepts Tested

Complex numbersCube roots of unityDe Moivre's TheoremEuler's form of complex numbers

Formulas Used

ω = e^(i2π/3)

ω^2 = e^(i4π/3)

z + 1/z = 2 Re(z)

ω + ω^2 + 1 = 0

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