$3^2\cdot3^3\cdot3^6$

$\frac{-19x^2+6x^3+20}{x^2-2x-3}$

$\frac{d}{dx}\left(x\sqrt{x^3+3}\right)$

$\int\frac{\left(x^2-x-1\right)}{x^3+2x^2-5x-6}dx$

$\left(x^{3+y^3}\right)dx-xy^2dy=0$

$6x^3+2x^3$

$\frac{1}{1+\cos^2\left(x\right)}=\frac{\sin^2\left(x\right)}{1+\cos^4\left(x\right)}$