两边对x求导得3z^2*z'x=yz+xyz'x在点(0,1,1)处z'x=1/3两边对y求导得3z^2*z'y=xz+xyz'y在点(0,1,1)处z'y=1/3所以切平面方程为-1/3(x-0)-1/3(y-1)+(z-1)=0法线方程(x-0)/(-1/3)=(y-1)/(-1/3)=(z-1)/1 ...
