MathDB
Question 2

Source:

December 6, 2015
quadraticsalgebrapolynomialRMO 2015

Problem Statement

Let P(x)=x2+ax+bP(x) = x^2 + ax + b be a quadratic polynomial with real coefficients. Suppose there are real numbers st s \neq t such that P(s)=tP(s) = t and P(t)=sP(t) = s. Prove that bstb-st is a root of x2+ax+bstx^2 + ax + b - st.