$\lim_{x\to2}\left(\frac{\cos\left(x\right)-\cos\left(\sin\left(2x\right)\right)}{x^2}\right)$

$-14xy^2+8xy^2$

$\frac{d}{dx}\left(\frac{x^7\left(x-5\right)^6}{\left(x^2+6\right)}\right)$

$\frac{3}{\sqrt{z+4}}$

$\left(x-12\right)\left(x-11\right)$

$\left(-\frac{\left(3\sqrt{10}\right)}{5}\right)=-\frac{\left(7\sqrt{10}\right)}{5}$