MathDB
A set with prod

Source: Indian RMO 2003 Problem 7

October 27, 2005
factorialratio

Problem Statement

Consider the set XX = {1,210}\{ 1,2 \ldots 10 \} . Find two disjoint nonempty sunsets AA and BB of XX such that a) AB=XA \cup B = X; b) xAx\prod_{x\in A}x is divisible by xBx\prod_{x\in B}x, where xCx\prod_{x\in C}x is the product of all numbers in CC; c) xAxxBx\frac{ \prod\limits_{x\in A}x}{ \prod\limits_{x\in B}x} is as small as possible.