$\sqrt{2-2\sqrt{2+\sqrt{50}+\sqrt{18-\sqrt{128}}}}$$=\sqrt{2-2\sqrt{2+\sqrt{50}+\sqrt{18-8\sqrt{2}}}}$$\sqrt{2-2\sqrt{2+\sqrt{50}+\sqrt{{{\left( 4-\sqrt{2} \right)}^{2}}}}}$
$=\sqrt{2-2\sqrt{2+5\sqrt{2}+4-\sqrt{2}}}$$=\sqrt{2-2\sqrt{6+4\sqrt{2}}}$$=\sqrt{2-2\sqrt{{{\left( 2+\sqrt{2} \right)}^{2}}}}$$=\sqrt{2-2\left( 2+\sqrt{2} \right)}$$=\sqrt{2-4-2\sqrt{2}}$
Con xem lại đề bài nhé