设函数在有界闭区域上连续，则是的https://img-ph-mirror.nosdn.127.net/AzSolBHpAcwrMwJeuCZ3qw==/6608821346933715540.pnghttps://img-ph-mirror.nosdn.127.net/7fwte4zRVRFsQA6AJGLNzQ==/6599274287471067843.pnghttps://img-ph-mirror.nosdn.127.net/JP8UrBsuml645rOhx1gFcw==/6608897213236161833.pnghttps://img-ph-mirror.nosdn.127.net/O_G3pHt3KyUzaRcmaobAmg==/6608234207725603267.png

设函数在点处存在关于和的一阶偏导数，则极限的值为.https://img-ph-mirror.nosdn.127.net/AzSolBHpAcwrMwJeuCZ3qw==/6608821346933715540.pnghttps://img-ph-mirror.nosdn.127.net/riflWFLWLx67TbwPlzd9tA==/6608437617375621610.pnghttps://img-ph-mirror.nosdn.127.net/dyIPWyFt4Slg58f2hJhSgA==/6599324865005947430.pnghttps://img-ph-mirror.nosdn.127.net/UdiS2LasHHPU1rvP0W8m0g==/6599309471843212852.pnghttps://img-ph-mirror.nosdn.127.net/9E39I3VJ73DxsgLGL8JhGg==/6608841138143042768.png

设是由圆周所围成的闭区域位于直线上方的部分，函数在上连续，则 ．https://img-ph-mirror.nosdn.127.net/7fwte4zRVRFsQA6AJGLNzQ==/6599274287471067843.pnghttps://img-ph-mirror.nosdn.127.net/SCWFbeCHt7KazxtYt1iHrw==/6608537672933918176.pnghttps://img-ph-mirror.nosdn.127.net/Bl8J31m4wDZC158XOpbd8A==/3773172062906460416.pnghttps://img-ph-mirror.nosdn.127.net/AzSolBHpAcwrMwJeuCZ3qw==/6608821346933715540.pnghttps://img-ph-mirror.nosdn.127.net/7fwte4zRVRFsQA6AJGLNzQ==/6599274287471067843.pnghttps://img-ph-mirror.nosdn.127.net/Ifzli-MewWUJphrm6hvdDA==/6608201222376771979.png