MathDB
There cannot be 5 distinct solutions [ILL 1971]

Source:

January 1, 2011
parameterizationalgebrasystem of equationsalgebra proposed

Problem Statement

Prove that the system of equations 2yz+xyz=a,2xzx+yz=a,2xyxy+z=a,2yz+x-y-z=a,\\ 2xz-x+y-z=a,\\ 2xy-x-y+z=a, aa being a parameter, cannot have five distinct solutions. For what values of aa does this system have four distinct integer solutions?