Don't know the steps in finding this derivative.
But the derivative is
The answer is:
/ x\ / x \ \e / | x 5*e *sin(5*x)| (cos(5*x)) *|e *log(cos(5*x)) - -------------| \ cos(5*x) /
/ x\ / 2 2 \ \e / | / 5*sin(5*x) \ x 25*sin (5*x) 10*sin(5*x) | x (cos(5*x)) *|-25 + |- ---------- + log(cos(5*x))| *e - ------------ - ----------- + log(cos(5*x))|*e | \ cos(5*x) / 2 cos(5*x) | \ cos (5*x) /
/ x\ / 3 3 2 / 2 \ \ \e / | / 5*sin(5*x) \ 2*x 265*sin(5*x) 250*sin (5*x) 75*sin (5*x) / 5*sin(5*x) \ | 10*sin(5*x) 25*sin (5*x)| x | x (cos(5*x)) *|-75 + |- ---------- + log(cos(5*x))| *e - ------------ - ------------- - ------------ - 3*|- ---------- + log(cos(5*x))|*|25 - log(cos(5*x)) + ----------- + ------------|*e + log(cos(5*x))|*e | \ cos(5*x) / cos(5*x) 3 2 \ cos(5*x) / | cos(5*x) 2 | | \ cos (5*x) cos (5*x) \ cos (5*x) / /