Solution of system with a parameter
Source: 2022 Israel TST 8 P1
May 21, 2022
algebraIMO 2022 tstsystem of equationsparameterization
Problem Statement
Let be an integer. Find all so that the system of equations in real variables :
\begin{align*}
&(r\cdot x_1-x_2)(r\cdot x_1-x_3)\dots (r\cdot x_1-x_n)=\\
=&(r\cdot x_2-x_1)(r\cdot x_2-x_3)\dots (r\cdot x_2-x_n)=\\
&\qquad \qquad \qquad \qquad \vdots \\
=&(r\cdot x_n-x_1)(r\cdot x_n-x_2)\dots (r\cdot x_n-x_{n-1})
\end{align*}
has a solution where the numbers are pairwise distinct.