$\lim_{z\to\:\:7}\left(\frac{z^2-5z-14}{z-7}\right)$

$\csc\left(2a\right)+\cot\left(4a\right)+\csc\left(4a\right)=\cot\left(a\right)$

$\left(x+2\right)\left(6x-1\right)$

$\ln\left(x+7\right)-\ln x=2$

$25x^2+100x+10$

$\frac{x}{5}=3$

$\left(\frac{1}{3}xy-z^6\right)\left(\frac{1}{3}xz+z^6\right)$