MathDB
Estonian Math Competitions 2005/2006

Source: Seniors Problem 2

July 30, 2008
quadraticsalgebracombinatorics unsolvedcombinatorics

Problem Statement

After the schoolday is over, Juku must attend an extra math class. The teacher writes a quadratic equation x^2\plus{} p_1x\plus{}q_1 \equal{} 0 with integer coefficients on the blackboard and Juku has to find its solutions. If they are not both integers, Jukumay go home. If the solutions are integers, then the teacher writes a new equation x^2 \plus{} p_2x \plus{} q_2 \equal{} 0, where p2 p_2 and q2 q_2 are the solutions of the previous equation taken in some order, and everything starts all over. Find all possible values for p1 p_1 and q1 q_1 such that the teacher can hold Juku at school forever.