Let the function defined on E = R$^2$ by J(x,y)=$x^2-xy +y^2+3x-2y+1$
Calculate the associated gradient and hessian? Deduce, the value of a local mimi point is what a strict mimimum
So the gradiant is : $(2x-y+3,2y-x-2)$
$1) 2x-y=-3$ and $2) 2y-x=3$ we can deduce 1) + 2) => y=0 $ and $ x=-1 $ or x=3/2$
J(x,y) -J(0,-1)==$x^2-xy +y^2+3x-2y+1-(1+3+1)=0 $
I made a mistake