MathDB
Putnam 1951 A1

Source:

May 25, 2022
Putnam

Problem Statement

Show that the determinant: 0abca0debd0fcef0 \begin{vmatrix} 0 & a & b & c \\ -a & 0 & d & e \\ -b & -d & 0 & f \\ -c & -e & -f & 0 \end{vmatrix} is non-negative, if its elements a,b,c,a, b, c, etc., are real.