\[x^{2} = 49\]
\[x = \pm 7.\]
\[D = 2^{2} - 4 \cdot 1 \cdot ( - 80) =\]
\[= 4 + 320 = 324\]
\[x_{1} = \frac{- 2 + \sqrt{324}}{2 \cdot 1} = \frac{- 2 + 18}{2} =\]
\[= \frac{16}{2} = 8\]
\[x_{2} = \frac{- 2 - \sqrt{324}}{2 \cdot 1} = \frac{- 2 - 18}{2} =\]
\[= - \frac{20}{2} = - 10\]
\[Ответ:нет\ решения.\]