//315
clear;
close;
clc;
disp('f(x,y)=2*x^2+4*x*y+y^2');
A=[2 2;2 1];
a=1;
c=1;
b=2;
disp(a*c,'ac=');
disp(b^2,'b^2=');
disp('Saddle point,as ac<b^2');