Write the function in the form $y=f(u)$ and $u=g(x)$. Then find $dy/dx$ as a function of $x$ $$y=\left(3x^2-(8/x)-x\right)^9$$
I know that $y = u^9$ and then $u = 3x^2-\dfrac{8}{x}-x$, but then I do not know how to put it together to solve for $dy/dx$. 

Hint: $$y=f(u), \space u=g(x) \implies \frac{dy}{dx} = \frac{dy}{du} \cdot \frac{du}{dx}$$
