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MathNet 2023-part-05 — 191 problems (EN–VI) Question 76

Math Olympiad Vault · MathNet 2023-part-05 — 191 problems (EN–VI)

Question 76

a) Prove that $x^2 + x + 1 \gt 0$ and $x^4 + x^3 + x^2 + x + 1 \gt 0$, for every real number $x$.

b) Find all real triples $(a, b, c)$ so that $a^8 + b^8 + c^8 = a^3 + b^3 + c^3$ and $a^5 + b^5 + c^5 = 3$.