function $f(x,y)=-x^2y(x+y-2)$ on the triangle $T$. I've done the following: Solving $\nabla f=0$ gives the points $(0,0), (0,1)$ and $0,2$. But when I compute the Hessian , I keep getting eigenvalue 0. Is there someone who can show me how to solve this problem? calculus multivariable-calculus share | improve this question