easy inequality (old problem)
Source: Netherlands 1994
June 28, 2009
inequalitiesalgebrapolynomialalgebra unsolved
Problem Statement
Three real numbers satisfy the inequality |ax^2\plus{}bx\plus{}c| \le 1 for all x \in [\minus{}1,1]. Prove that |cx^2\plus{}bx\plus{}a| \le 2 for all x \in [\minus{}1,1].