设z=z(x,y)由方程x2+2y2+3z2+xy-z=9确定,求∂z/∂x,∂z/∂y.
令F(x,y,z)=x2+2y2+3z2+xy-z-9,则 F′x=2x+y,F′y=4y+x,F′z=6z-1, 于是,∂z/∂x=-(F′x/F′z)=-[(2x+y)/(6z-1)], ∂z/∂y=-(F′y/Fz)=-[(4y+x)/(6z-1)].
设z=z(x,y)由方程x2+2y2+3z2+xy-z=9确定,求∂z/∂x,∂z/∂y.
令F(x,y,z)=x2+2y2+3z2+xy-z-9,则 F′x=2x+y,F′y=4y+x,F′z=6z-1, 于是,∂z/∂x=-(F′x/F′z)=-[(2x+y)/(6z-1)], ∂z/∂y=-(F′y/Fz)=-[(4y+x)/(6z-1)].