$\lim_{x\to-3}\left(\frac{x^2-8x-13}{x^2-5}\right)$

$\frac{\cot\left(t\right)+\tan\left(t\right)}{sec\left(-t\right)}=\csc\left(t\right)$

$12mn+8n-3n-2$

$\int\frac{x}{\left(4-x\right)^3}dx$

$\left|\left(6\right)\left(2\right)\right|$

$\frac{x+1}{x+2}=\frac{y}{x-1}$

$s^3+4s^2+3s$