1.分母极限为0,分式极限存在,则分子极限为0,得 z=f(x,y)=2x-y+2,z'=2,z'=-1,dz=2dx-dy,dz|(0,1)=2dx-dy.4.W =∫Pdx+Qdy+Rdz =∫xdx-ydy+zdz M1M2 的参数方程 x=t,y=2t,z=3t,得W =∫(t-2t*2+3t*3)dt =∫6tdt = 3.5 积...
1.分母极限为0,分式极限存在,则分子极限为0,得 z=f(x,y)=2x-y+2,z'=2,z'=-1,dz=2dx-dy,dz|(0,1)=2dx-dy.4.W =∫Pdx+Qdy+Rdz =∫xdx-ydy+zdz M1M2 的参数方程 x=t,y=2t,z=3t,得W =∫(t-2t*2+3t*3)dt =∫6tdt = 3.5 积...