Finite ring with unique solution
Source: RMO 2008, Grade 12, Problem 3
April 30, 2008
Ring Theorylinear algebramatrixnumber theoryleast common multiplesearchgroup theory
Problem Statement
Let be a unitary finite ring with elements, such that the equation x^n\equal{}1 has a unique solution in , x\equal{}1. Prove that
a) is the only nilpotent element of ;
b) there exists an integer , such that the equation x^k\equal{}x has solutions in .