Solución
∂
2
z
∂
x
2
=
2
,
∂
2
z
∂
y
2
=
4
\frac{\partial^2 z}{\partial x^2}=2,\;\;\frac{\partial^2 z}{\partial y^2}=4
∂
x
2
∂
2
z
=
2
,
∂
y
2
∂
2
z
=
4