$$\mathit{一种}=\left[\begin{array}{ccc}{\mathit{一种}}_{11.}& {\mathit{一种}}_{12.}& {\mathit{一种}}_{13.}\\ {\mathit{一种}}_{21.}& {\mathit{一种}}_{22.}& {\mathit{一种}}_{23.}\\ {\mathit{一种}}_{31.}& {\mathit{一种}}_{32.}& {\mathit{一种}}_{33.}\end{array}\right]=\left[\begin{array}{ccc}1& -5.& 2\\ -3.& 7.& 9.\\ 4.& -1& 6.\end{array}\right]那$$

$$\mathrm{TR.}（\mathit{一种}）=\underset{\mathit{一世}=1}{\overset{3.}{\sigma .}}{\mathit{一种}}_{\mathrm{II}}={\mathit{一种}}_{11.}+{\mathit{一种}}_{22.}+{\mathit{一种}}_{33.}=1+7.+6.=14.。$$