\[\boxed{\text{1281.\ }\text{еуроки}\text{-}\text{ответы}\text{\ }\text{на}\text{\ }\text{пятёрку}}\]
\[y = \sqrt{20 + 2\sqrt{91 + 6x - x^{2}}} -\]
\[- \sqrt{20 - 2\sqrt{91 + 6x - x^{2}}}\]