Chapter 14.2, Problem 34E

If $f(x,y)=x^3+\ln (xy-1)$, find the following.

$(\text{a})\frac{{\partial }^{2}f}{\partial x^2}(\text{b})\frac{{\partial }^{2}f}{\partial y^2}(\text{c})\frac{{\partial }^{2}f}{\partial x\partial y}(\text{d})\frac{{\partial }^{2}f}{\partial y\partial x}$