$\displaystyle \int\frac{2cos^2(2t)-1}{1+3sin4t}dx$

$\displaystyle \int\frac{cot^2ln(1-x)}{1-x}dx$

$\displaystyle \int\frac{tan^2e^-x}{e^x}dx$

I am having problems with simplifying the given, before I can Integrate.

For example, the problem 1, my u is the denominator, but after deriving the u It is still impossible to solve it, same problem applies to problem 2. For number I just can't solve it

any help is appreciated, thank you