<img class=jc-formula data-tex=\begin{ vmatrix } 3 \begin{ matrix } 0 0 \end{ matrix } \\ 2 \begin{ matrix } -5 2 \end{ matrix } \\ -7 \begin{ matrix } 2 1 \end{ matrix } \end{ vmatrix }=3\begin{ vmatrix } -5 2 \\ 2 -1 \end{ vmatrix } src=https://huaweicloudobs.ahjxjy.cn/28B8975C0852EE749D3C3C69740C1FC7.png style=vertical-align: middle;/>