$\int\frac{tan^2\left(x\right)}{sin\left(2x\right)}dx$

$\left(3m+2m\right)\left(3m+2n\right)$

$2x^3-4x^2+20\:$

$\lim_{x\to\infty}\left(\frac{7\sqrt{4n+21}}{\sqrt{n}}\right)\left(\frac{n+1}{2}\right)$

$\frac{23x^4+8x^3}{4x^3}$

$\sqrt{x}^{18}$

$\left(1-n^4\right)\left(1+n^2\right)$