$\left(7x^2\:-\:12y^3\right)\left(7x^2\:\:+\:12y^3\right)$

$\int\frac{e}{1+e^{-x}}\:dx$

$4x^2+2x+2$

$\cot\left(2a\right)=\frac{1}{2}\left(\cot a-\tan a\right)$

$\left(x-2\right)^2\ge\:\:0$

$\frac{-\frac{2}{\pi}sen\left(\frac{\pi}{2}n\right)}{n}+\frac{\frac{1}{\pi}sen\left(\frac{\pi}{2}n\right)}{n}$

$\frac{\left(1-cos^2x\right)}{csc^3x}$