Find the derivative $\frac{d}{dx}\left(\frac{x}{x^2+1}\right)$

Find the derivative

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

Find the derivative

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

Find the derivative

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

Find the derivative

$\frac{d}{dt}\left(\frac{\sqrt{t-4}}{tcos\left(t\right)}\right)$

Find the derivative

$\frac{d}{dx}\left(\frac{\left(x^5+3x\right)^4}{cos\:x}\right)$

Find the derivative

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

Find the derivative

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