$\frac{a^2-6a}{a^3+3a^2}$

$\frac{7}{x^3}\frac{d}{dx}$

$\frac{c^2+12c+36}{c+9}$

$\lim_{x\to\frac{3}{2}}\left(\frac{4x^2-9}{8x^3-27}\right)$

$y=xy+3y-x-3$

$\int\frac{x^3+6}{4x^3-4x^2}dx$

$\left(\csc\left(x\right)^2-1\right)\left(\tan\left(x\right)^2+1\right)=\csc\left(x\right)^2$