$$f(x,y)= x^3 +y^2 − 2xy + x $$
$$\frac{\partial f(x,y)}{\partial x}= \cdots $$
$$\frac{\partial f(x,y)}{\partial y}= \cdots $$
$$\frac{\partial f^2(x,y)}{\partial x \partial x}= \cdots $$
$$\frac{\partial f^2(x,y)}{\partial x \partial y}= \cdots $$
$$\frac{\partial f^2(x,y)}{\partial y\partial x}= \cdots $$
$$\frac{\partial f^2(x,y)}{\partial y\partial y}= \cdots $$