Hi to all ! (Happy)

I have this function :

I should find the critical point.

http://en.wikipedia.org/wiki/Critica..._(mathematics)

the system of first derivative :

solutions :

then I should study the hessian matrix to understand the type of points

The determinant of Hessian is :

(where )

in this is a point of Minimun

The question :

P2 and P3 are points of saddle ? (Crying)