$$ \int \frac{2 x^2 \cos x^2-\sin x^2}{x^2} d x= $$

If $\int \frac{\log \left(1+x^4\right)}{x^3} d x=f(x) \log \left(\frac{1}{g(x)}\right)+\tan ^{-1}$ $(h(x))+c$, then $h(x)\left[f(x)+f\left(\frac{1}{x}\right)\right]=$

Let $f(x)=\int \frac{x}{\left(x^2+1\right)\left(x^2+3\right)} d x$. If $f(3)=\frac{1}{4} \log \left(\frac{5}{6}\right)$, then $f(0)=$

$$ \int \frac{2 \cos 2 x}{(1+\sin 2 x)(1+\cos 2 x)} d x= $$