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13th Annual Harvard-MIT Mathematics Tournament #0j1z

13th Annual Harvard-MIT Mathematics TournamentHard

From module Roots of Unity (Advanced)

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Understand the scale
Scale 0.5: Easiest math competition problems, often solvable even for early middle school students without experience. 1: Problems strictly for beginners, often at a moderate middle school level. 1.5: Problems for stronger beginner students, on the level of the middling problems in most middle school contests. 2: For motivated beginners, harder questions from the previous categories. 2.5: More advanced beginner problems, hardest questions from previous categories. 3: Early intermediate problems that require more creative thinking. 3.5: Tougher early intermediate problems that consistently stretch into higher-level creative thinking or conceptual knowledge. 4: Intermediate-level problems. 4.5: Upper intermediate problems approaching the upper bound for non-invitational sprint math competitions. 5: More difficult AIME problems or simple proof-based Olympiad-style problems. 6: High-level AIME-styled questions or introductory Olympiad-level questions. 7: Tougher Olympiad-level questions, may require more technical knowledge. 8: High-level Olympiad-level questions. 9: Expert Olympiad-level questions. 9.5: The hardest problems appearing on Olympiads which the strongest students could reasonably solve. 10: Historically notorious problems, generally unsuitable for even very hard competitions because they are exceedingly tedious, long, and difficult.
Roots of unityPolynomial operationsComplex numbers

Problem

Problem: Suppose that there exist nonzero complex numbers aa, bb, cc, and dd such that kk is a root of both the equations ax3+bx2+cx+d=0a x^{3} + b x^{2} + c x + d = 0 and bx3+cx2+dx+a=0b x^{3} + c x^{2} + d x + a = 0. Find all possible values of kk (including complex values).

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