\[y^{2} - 8y - 7 = 0\]
\[D_{1} = 16 + 7 = 23\]
\[y_{1} = 4 + \sqrt{23};\ \]
\[y_{2} = 4 - \sqrt{23}.\]
\[Ответ:y = 4 \pm \sqrt{23}.\]