Ответ:

[tex]7\sqrt{2}[/tex]

Решение:

[tex]3\sqrt{8}-\sqrt{50}+2\sqrt{18}=3\sqrt{4*2}-\sqrt{25*2}+2\sqrt{9*2}=\\\\=3\sqrt{2^2*2}-\sqrt{5^2*2}+2\sqrt{3^2*2}=3*2\sqrt{2}-5\sqrt{2}+2*3\sqrt{2}=\\\\=6\sqrt{2}-5\sqrt{2}+6\sqrt{2}=7\sqrt{2}[/tex]

[tex]\displaystyle 3\sqrt{8}-\sqrt{50} +2\sqrt{18}=6\sqrt{2}-5\sqrt{2}+6\sqrt{2}=7\sqrt{2}[/tex]