2.72: Logarithmic curve and integration

0606/23/O/N/17 — Question 9 · 9 marks

(i)
Show that ddx(lnxx3)=13lnxx4\dfrac{\mathrm{d}}{\mathrm{d}x}\left(\dfrac{\ln x}{x^{3}}\right) = \dfrac{1 - 3\ln x}{x^{4}}.
[3]
(ii)
Find the exact coordinates of the stationary point of the curve y=lnxx3y = \dfrac{\ln x}{x^{3}}.
[3]
(iii)
Use the result from part (i) to find lnxx4dx\displaystyle\int \frac{\ln x}{x^{4}}\,\mathrm{d}x.
[4]