Câu hỏi 2
Đánh giá sản phẩm $$
\begin{gathered} (\sqrt5+\sqrt6+\sqrt7)\\ {}\cdot(-\sqrt5+\sqrt6+\sqrt7)\\ {}\cdot(\sqrt5-\sqrt6+\sqrt7)\\ {}\cdot(\sqrt5+\sqrt6-\sqrt7). \end{gathered}
$$
\begin{gathered} (\sqrt5+\sqrt6+\sqrt7)\\ {}\cdot(-\sqrt5+\sqrt6+\sqrt7)\\ {}\cdot(\sqrt5-\sqrt6+\sqrt7)\\ {}\cdot(\sqrt5+\sqrt6-\sqrt7). \end{gathered}
$$