$\frac{\left(x+4y\right)\left(5x-20y\right)}{2}$

$2x+2a,para\:x=\:6\:y\:a=4$

$\left(-n+3\right)\left(4n+5\right)$

$\sqrt{\infty-\infty+8}$

$\ln\left(x\right)+\ln\left(x-2\right)=\ln\left(2x\right)$

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

$\frac{d}{dx}\left(cos^{-1}\left(\tanh\:\left(2x\right)\right)\right)$