\[x^{2} + 9x - 10 = (x - 1)(x + 10)\]
\[D = 81 + 40 = 121\]
\[x_{1} = \frac{- 9 + 11}{2} = 1;\]
\[x_{2} = \frac{- 9 - 11}{2} = \ - 10.\]
\[Ответ:x^{2} + 9x - 10 = (x - 1)(x + 10).\]