If z=z(x,y), we can go through the motions of calculating ∂z∂x and ∂z∂y, and we can then further calculate the second derivatives \(...If z=z(x,y), we can go through the motions of calculating ∂z∂x and ∂z∂y, and we can then further calculate the second derivatives ∂2z∂x2, ∂2x∂y2, ∂2z∂y∂x and ∂2z∂y∂x.