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USA TSTST #0k5c

USA TSTSTHard

From module Functional Equations II

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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.
Functional EquationsPolynomialsDivisibility / Factorization

Problem

As usual, let Z[x]\mathbb{Z}[x] denote the set of single-variable polynomials in xx with integer coefficients. Find all functions θ:Z[x]→Z\theta : \mathbb{Z}[x] \to \mathbb{Z} such that for any polynomials p,q∈Z[x]p, q \in \mathbb{Z}[x],

  • θ(p+1)=θ(p)+1\theta(p + 1) = \theta(p) + 1, and
  • if θ(p)≠0\theta(p) \neq 0 then θ(p)\theta(p) divides θ(p⋅q)\theta(p \cdot q).

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