f(x,y)=3x^2-6xy+2y^3
(1)
fx(x,y)=6x-6y
fy(x,y)=-6x+6y^2
fxx(x,y)=6
fxy(x,y)=fyx(x,y)=-6
fyy(x,y)=12y
(2)
fx(x,y)=6x-6y=0 : x=y
fy(x,y)=-6x+6y^2=0 : x=y^2
を満たす点(停留点)と停留値は
(0,0), f(0,0)=0
(1,1), f(1,1)=-1
https://www.momoyama-usagi.com/entry/math-analysis20
