$\begin{align}&Cho\,\text{a,b,c0thoa}\!\!\hat{\mathrm{u}}\!\!\text{abc}\left(a+b+c\right)=4.\,T\grave{i}m\,gia\grave{u}\,tr\grave{o}\,nho\hat{u}\,nha\acute{a}t\,cu\hat{u}a\,bieu\,th\ddot{o}\grave{u}c: \\& P=\frac{1}{\sqrt{\left( a+b \right)\left( a+c \right)}}-\frac{8bc}{bc\left( {{b}^{2}}+{{c}^{2}} \right)+18} \\\end{align}$
Edited by santo3vong, 28-02-2016 - 10:07.
