Posted by haifeng on 2012-07-26 09:40:17 last update 2012-07-26 10:19:02 | Answers (0) | 收藏
证明:
\[ \begin{vmatrix} x_1 & y_1 & z_1\\ x_2 & y_2 & z_2\\ x_3 & y_3 & z_3 \end{vmatrix}^2\leqslant(x_1^2+x_2^2+x_3^2)(y_1^2+y_2^2+y_3^2)(z_1^2+z_2^2+z_3^2). \]