Simplify the expression $\frac{ab}{a}$

$\frac{d}{dx}\left(\arcsin\left(4x^2\right)\right)$

Find the derivative

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

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

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

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

$\frac{d}{dx}\left(\arcsin\left(4x\right)\right)$

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