tự xét đk (xét sau)
\(\sqrt{x+8+2\sqrt{x+7}}=\left|\sqrt{x+7}+1\right|=\sqrt{x+7}+1\)
\(pt\Leftrightarrow\sqrt{x+1-\sqrt{x+7}}=3-\sqrt{x+7}\)
đk x>=2
\(x+1-\sqrt{x+7}=9-6\sqrt{x+7}+x+7\)
\(5\sqrt{x+7}=15\Leftrightarrow\sqrt{x+7}=3\Leftrightarrow x=2\)