![](https://blog.hocmai.vn/wp-content/uploads/2017/07/hot.gif)
![](https://blog.hocmai.vn/wp-content/uploads/2017/07/hot.gif)
Cho $\left\{\begin{matrix} a,b,c>0 & & \\ abc=1 & & \end{matrix}\right.$. Tìm GTNN của
$$P=\dfrac{a^3}{(1+b)(1+c)}+\dfrac{b^3}{(1+c)(1+a)+\dfrac{c^3}{(1+a)(1+b)}$$
$$P=\dfrac{a^3}{(1+b)(1+c)}+\dfrac{b^3}{(1+c)(1+a)+\dfrac{c^3}{(1+a)(1+b)}$$