<p>函数<img src="https://learnfile.20230611.cn/learnAppQuestion/22/cd/22cd62e6c29b4a071961faa467fecb63.jpg" style="width: 100%;height: auto;">的全微分<img src="https://learnfile.20230611.cn/learnAppQuestion/99/8f/998f047401ce2218acefa9a367d1884b.jpg" style