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x^3 + ax^2 + bx + c.=0, 3 real roots - VI Soros Olympiad 1999-00 Round 1 11.1

Source:

May 21, 2024
algebrapolynomial

Problem Statement

The game involves two players AA and BB. Player AA sets the value of one of the coefficients a,ba, b or cc of the polynomial x3+ax2+bx+c.x^3 + ax^2 + bx + c. Player BB indicates the value of any of the two remaining coefficients . Player AA then sets the value of the last coefficients. Is there a strategy for player A such that no matter how player BB plays, the equation x3+ax2+bx+c=0x^3 + ax^2 + bx + c = 0 to have three different (real) solutions?