\[\boxed{\text{1295.\ }\text{еуроки}\text{-}\text{ответы}\text{\ }\text{на}\text{\ }\text{пятёрку}}\]
\[y = \sqrt{x^{2} + 2\sqrt{2x} + 2} +\]
\[+ \sqrt{x^{2} - 2\sqrt{2x} + 2}\]
\[при\ \ \ \ - \sqrt{2} \leq x \leq \sqrt{2}\]
\[y = \sqrt{\left( x + \sqrt{2} \right)^{2}} + \sqrt{x - \sqrt{2}} =\]
\[= \left| x + \sqrt{2} \right| + \left| x - \sqrt{2} \right|\]
\[y = x + \sqrt{2} - x + \sqrt{2} = 2\sqrt{2}\]
\[y = 2\sqrt{2} - линейная\ функция.\]