$\lim_{u\to\frac{\pi}{4}}\left(\frac{tan\left(u\right)-cot\left(u\right)}{2u-\frac{\pi}{2}}\right)$

$\frac { n } { n }$

$x^2-\frac{5}{4}x$

$m\:\left(x\:+\:y\right)\:-\:2n\:\left(x\:+\:y\right)\:+\:4\:a\:\left(x\:+\:y\right)$

$a=2;b=5;c=-3;d=-1;f=0$

$\frac{\left(9x^4-24x^3-3x^2+8x\right)}{\left(x-1\right)}$

$2x-4<x+3$