bài 1: giải phương trình

$\displaystyle \begin{array}{{>{\displaystyle}l}} \sqrt{x+2\sqrt{2x-4}} +\sqrt{x-2\sqrt{2x-4}} =2\sqrt{2}\\ \sqrt{x+2\sqrt{2}\sqrt{x-2}} +\sqrt{x-2\sqrt{2}\sqrt{x-2}} =2\sqrt{2}\\ \sqrt{x-2+2.\sqrt{2} .\sqrt{x-2} +2} +\sqrt{x-2-2.\sqrt{2}\sqrt{x-2} +2} =2\sqrt{2}\\ \sqrt{\left(\sqrt{x-2} +\sqrt{2}\right)^{2}} +\sqrt{\left(\sqrt{x-2} -\sqrt{2}\right)^{2}} =2\sqrt{2}\\ |\sqrt{x-2} +\sqrt{2} |+|\sqrt{x-2} -\sqrt{2} |=2\sqrt{2} \ \\ \sqrt{x-2} +\sqrt{2} +|\sqrt{x-2} -\sqrt{2} |=2\sqrt{2}\\ |\sqrt{x-2} -\sqrt{2} |=\sqrt{2} -\sqrt{x-2} \ \\ \rightarrow \sqrt{x-2} -\sqrt{2} \leqslant 0\ \\ \rightarrow x\leqslant 4\ \\ \end{array}$