How can I find the global min/max in this problem?
Find the critical points of the function :
f(x,y)=$2x^3-3x^2y-12x^2-3y^2$
and determine their type.
Are there any global min/max?
The critical points were: (0,0),
(2,-2),(-4,-8)
By using the hessian matrix I found their types:
(0,0) is a local maximum
(-4,-8) is a saddle
(2,-2) is a saddle.
But I do not understand how to find the global minimum or maximum.
I know that if the Hessian matrix is negative semi definite then any local max is a global max and if Hessian matrix is a positive semi definite then any local min is a global min.
Please help me to find the global minimum /maximum?