设:F(x,y,z) = x^3+y^3+z^3+xyz-6 .
则:Fx(x,y,z,)=3x^2+yz, Fy(x,y,z,)=3y^2+xz, Fz(x,y,z,)=3z^2+xy,
Fx(1,2.-1) =3+(-2)=1, Fy(1,2,-1) =12-1=11, Fz(1,2,-1)= 3+2=5.
故: 切平面方程为:(x-1) +11(y-2) +5(z+1)=0
设F(x,y,z)=x^3+y^3+z^3+xyz-6
Fx=3x^2+yz Fy=3y^2+xz Fz=3z^2+xy
gradF(1,2,-1)={1,11,5}
切平面方程为(x-1)+11(y-2)+5(z+1)=0
f(X,Y,Z)=X^3+Y^+Z^3+XYZ-6,fx=3X^2,fy=3Y^2,fz=3Z^2,求雅各比