Alan G. answered 06/19/16
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Zicon,
Please verify that THIS is the problem:
Prove: (a + bω + cω²)³ + (a + bω² + cω)³ = 27abc,
Given: a + b + c = 0.
(This reminds me of an old Putnam Exam or IMO question from many years ago. Where did you get it?)