(i) Show that

\(\frac{d}{dx}\left(\frac{\ln x}{x^3}\right)=\frac{1-3\ln x}{x^4}.\)

(ii) Find the exact coordinates of the stationary point of the curve \(y=\dfrac{\ln x}{x^3}\).

(iii) Use the result from part (i) to find \(\displaystyle\int \dfrac{\ln x}{x^4}\,dx\).