Rút gọn: 2/x^2 - y^2.căn bậc hai của 3(x + y)^2/4

* Hướng dẫn giải

$\begin{array}{l}\frac{2}{x^2-y^2}\sqrt{\frac{3{\left(x+y\right)}^2}{4}}=\frac{2}{\left(x-y\right)\left(x+y\right)}.\frac{\sqrt{3}}{2}\sqrt{{\left(x+y\right)}^2}\\ =\frac{\sqrt{3}.\left|x+y\right|}{\left(x-y\right)\left(x+y\right)}=\left[\begin{array}{l}\frac{\sqrt{3}\left(x+y\right)}{\left(x-y\right)\left(x+y\right)}=\frac{\sqrt{3}}{x-y}(neux+y>0)\\ \frac{\sqrt{3}\left(x+y\right)}{\left(x-y\right)\left(x+y\right)}=\frac{-\sqrt{3}}{x-y}(neux+y<0)\end{array}\right.\end{array}$