∂ ^2z/ ∂ x^2=[m](\frac{1}{1+(x-3y)^2})`_{x}=-\frac{1}{(1+(x-3y)^2)^2}[/m]
∂ z/ ∂ y=[m]\frac{1}{1+(x-3y)^2}\cdot (x-3y)`_{y}=-\frac{3}{1+(x-3y)^2}[/m]
∂ ^2z/ ∂ y^2=[m](-3\frac{1}{1+(x-3y)^2})`_{y}=9\frac{1}{(1+(x-3y)^2)^2}[/m]
∂ z/ ∂ x=[m]\frac{1}{1+(x-3y)^2}\cdot (x-3y)`_{x}\frac{1}{1+(x-3y)^2}[/m]
∂ ^2z/ ∂ x ∂ y=[m](\frac{1}{1+(x-3y)^2})`_{y}=-\frac{3}{(1+(x-3y)^2)^2}[/m]