二元函数<img src=https://huaweicloudobs.ahjxjy.cn/3B4502C5C5DFF2F6242ABF3CB84260B2.png title=]XK95M8]_U7H5QN_RXG%C8R.png alt=]XK95M8]_U7H5QN_RXG%C8R.png/>
①
<img src=https://huaweicloudobs.ahjxjy.cn/C9AEE107ECF19732E45761119CBA141F.png title=4LTY~D@QL16QR3)]3ESX96U.png alt=4LTY~D@QL16QR3)]3ESX96U.png/>
②
<img src=https://huaweicloudobs.ahjxjy.cn/5F2FD6F9D14C2F7DE491F07C1343F256.png title=6$4U96KJW`10WH][1BO}C)0.png alt=6$4U96KJW`10WH][1BO}C)0.png/>
③
<img src=https://huaweicloudobs.ahjxjy.cn/DAEDF46C28A86A7851D2919E7C3A2A0F.png title=CHANV){}PQPJYW~$J3O77MD.png alt=CHANV){}PQPJYW~$J3O77MD.png/>
④
<img src=https://huaweicloudobs.ahjxjy.cn/715D1E66A9E44F684956EDF7CD8E0BE2.png title=S2R@H%XAW@RV`MK7D]PUM41.png alt=S2R@H%XAW@RV`MK7D]PUM41.png/>