Encontre a derivada $\frac{d}{dx}\left(\frac{x}{e^{-x}}\right)$

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

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

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

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

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

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

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