Find the integral $\int\frac{\arctan\left(x\right)}{x}dx$

$\frac{d}{dx}\left(\frac{3}{x^2}\right)$

$\frac{d}{dx}\left(\sqrt{\frac{x\left(x+2\right)}{\left(2x+1\right)\left(5x+3\right)}}\right)$

$\frac{d}{dx}\left(\frac{5}{x}\right)$

$\frac{d}{dx}\left(\frac{\ln\left(x\right)}{x}\right)$

$\frac{d}{dx}\left(\frac{\left(x^3+1\right)^4sin^2x}{x^{\frac{1}{3}}}\right)$

$\frac{d}{dx}\left(\frac{e^x}{\sqrt{x}}\right)$

$\frac{d}{dx}\left(\frac{-x}{y}\right)$