x = linspace(-2,2,9);
y = x;
[X, Y] = meshgrid(x,y);
Z = 95+0.05*X-0.145*Y-8.13*X.^2-5.87*Y.^2-6.25*X.*Y;
contour(X,Y,Z,'ShowText','on')
xlabel('x')
ylabel('y')
zlabel('z')
grid
