Find the derivative $\frac{d}{dx}\left(\frac{1}{x^7}\right)$

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

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

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

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

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

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

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