MathDB
root of polynomial

Source: 30-th Vietnamese Mathematical Olympiad 1992

February 17, 2007
algebrapolynomialalgebra unsolved

Problem Statement

Let 9<n1<n2<<ns<1992 9 < n_{1} < n_{2} < \ldots < n_{s} < 1992 be positive integers and P(x) \equal{} 1 \plus{} x^{2} \plus{} x^{9} \plus{} x^{n_{1}} \plus{} \cdots \plus{} x^{n_{s}} \plus{} x^{1992}. Prove that if x0 x_{0} is real root of P(x) P(x) then x_{0}\leq\frac {1 \minus{} \sqrt {5}}{2}.