① <imgdata-url="doc/a@8CE0393037E3C3D943041E145EEB4761.jpg"data-preview_url_ueditor="doc/a@8CE0393037E3C3D943041E145EEB4761.jpg"src="http://121.251.253.213/doc/a@8CE0393037E3C3D943041E145EEB4761.jpg/download?time=636154229957298238&token=C9C2E01C18DF968BF18A561EE6D28018&filename=jpg"/>
② <imgdata-url="doc/a@49F92E671A48830B9035FC09CA669E29.png"data-preview_url_ueditor="doc/a@49F92E671A48830B9035FC09CA669E29.png"src="http://121.251.253.213/doc/a@49F92E671A48830B9035FC09CA669E29.png/download?time=636154243790934535&token=966B0922A385F1CAAF1A0F74F8145369&filename=png"/>
③ <imgdata-url="doc/a@601D71E67089BFF64E8F11762FB6EBBF.jpg"data-preview_url_ueditor="doc/a@601D71E67089BFF64E8F11762FB6EBBF.jpg"src="http://121.251.253.213/doc/a@601D71E67089BFF64E8F11762FB6EBBF.jpg/download?time=636154230245430744&token=2E24D661642E464AF075DA971E067A53&filename=jpg"/>
③ 设A为<img class=jc-formula data-tex=m\times n src=https://huaweicloudobs.ahjxjy.cn/68A6AD364CE4B73E12720634B9824451.png style=vertical-align: middle;/>矩阵,则<img class=jc-formula data-tex={ E }_{ m }A=A{ E }_{ n }=A src=https://huaweicloudobs.ahjxjy.cn/50161268882F10BEB7C0E76436FB19D4.png style=vertical-align: middle;/>