\[x^{2} - 4x - 140 = 0\]
\[D = ( - 4)^{2} - 4 \cdot 1 \cdot ( - 140) =\]
\[= 16 + 560 = 576\]
\[\sqrt{D} = \sqrt{576} = 24\]
\[x_{1} = \frac{4 + 24}{2} = \frac{28}{2} = 14\]
\[x_{2} = \frac{4 - 24}{2} = \frac{- 20}{2} = - 10\]
\[Ответ:14;\ - 10.\]