$\frac{-\sin\left(x\right)}{1-\left(\cos\left(x\right)\right)^2}$

$\lim_{t\to2}\left(\frac{x^3-8}{x-2}\right)$

$5x\:-\:2y\:+\:z\:-\:2w=1$

$\sqrt{x-1}^2+2\sqrt{x-1}-1$

$4n\cdot3n^4$

$1+3\left(5a+4\right)$

$-2-\left(+30\right)-\left(+16\right)-\left(-50\right)-\left(-73\right)$