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 and are the solutions of the previous equation taken in some order, and everything starts all over. Find all possible values for and such that the teacher can hold Juku at school forever.