2.67: Secant derivative and logarithmic integration

0606/23/M/J/20 — Question 12 · 11 marks

(a)(i)
Given that f(x)=1cosxf(x) = \dfrac{1}{\cos x}, show that f(x)=tanxsecxf'(x) = \tan x \sec x.
[3]
(a)(ii)
Hence find (3tanxsecxe3x4)dx\displaystyle\int \left(3\tan x \sec x - \sqrt[4]{\mathrm{e}^{3x}}\right)\mathrm{d}x.
[3]
(b)
Given that 25ppx+10dx=ln2\displaystyle\int_{2}^{5} \frac{p}{px + 10}\,\mathrm{d}x = \ln 2, find the value of the positive constant pp.
[5]