设有连续的偏导数，且，则 =（ ）。http://image.zhihuishu.com/zhs/onlineexam/ueditor/201803/63eb2ad0bac447489cbf8cbb923d3692.png
举一反三
- 设 有连续的偏导数， 且 ，则 =（ ）。http://image.zhihuishu.com/zhs/onlineexam/ueditor/201803/63eb2ad0bac447489cbf8cbb923d3692.png
- 函数在点处是连续的且偏导数也是存在的。（ ）http://image.zhihuishu.com/zhs/onlineexam/ueditor/201803/66eeff13d1904738bea6f4255ed45e69.png
- 若http://image.zhihuishu.com/zhs/onlineexam/ueditor/201908/5c06779096154f7c8b702d66edce8df1.png在点http://image.zhihuishu.com/zhs/onlineexam/ueditor/201908/7d26b1d151c9438485fa20b9ca38af20.png处可微，则偏导数http://image.zhihuishu.com/zhs/onlineexam/ueditor/201908/518027493bf540a1a080f49503d0afb3.png一定连续。<br>
- 内压球形容器的应力为： A: <img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201803/7a7e20156c8c4502840fc258ffe21c74.png"> B: <img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201803/6b137ba6e7464b2c8122eced2a3d45cd.png"> C: <img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201803/3c032f5116a04b288400df17925e39c2.png"> D: <img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201803/85ca21668f4045e2b864897bc3795fdf.png">
- 若偏导数http://image.zhihuishu.com/zhs/onlineexam/ueditor/201908/a1b21fe4866c4a31bc3d618a2ea3c815.png存在，则http://image.zhihuishu.com/zhs/onlineexam/ueditor/201908/7cb9e1dd6acf40e6abfc4d2b731eeef2.png在点http://image.zhihuishu.com/zhs/onlineexam/ueditor/201908/e1a9c8e68bfc4a8f949807cf6c5f0a12.png处连续。<span style="font-family: 宋体;</span><br><br>