Is there anybody here who know hows to solve any of the problems below? I've tried some methods but none of then worked.

$\displaystyle

\int \frac{cos(x)}{x^2+a^2}\,dx

$

$\displaystyle

\int \frac{xsin(x)}{x^2+a^2}\,dx

$

$\displaystyle

\int \frac{x^\frac{1}{3}}{x^2+1}\,dx

$

$\displaystyle

\int \frac{log(x)}{x^2+1}\,dx

$

It would be really helpfull if anybody knows any of the problems above.

Thanks for the help