$\lim_{u\to\frac{\pi}{4}}\left(\frac{8\tan\left(u\right)-8\cot\left(u\right)}{u-\frac{\pi}{4}}\right)$

$x^3+5x^2-x-5$

$4x^2\:-25x+36$

$\lim_{z\to2}\left(\frac{z^2+4}{z-2}\right)$

$\frac{\csc\left(t\right)-\sin\left(t\right)}{\csc\left(t\right)}$

$2x+1\cdot x^2+4x-2$

$-\left(14\right)-1$