$3\cdot\left(a+2\right)\cdot\left(a-1\right)$

$\left(x+3\right)+\left(x-3\right)-\left(x+3\right)^2+18$

$\frac{dr}{dx}+r\tan\left(x\right)=9\tan\left(x\right)$

$-5k\:-\:6\:+\:9k\:+\:19$

$100m^2n^2-169y^6$

$\int\:\:\left(\frac{m^2+1}{m^2-m}\right)dm$

$\int\frac{x+1}{x^2\left(x-1\right)}dx$