\[y = \frac{x^{2} - 8x - 9}{x + 1} =\]
\[= \frac{(x + 1)(x - 9)}{x + 1} =\]
\[= x - 9;\ \ x \neq - 1.\]
\[x^{2} - 8x - 9 = (x + 1)(x - 9)\]
\[D_{1} = 16 + 9 = 25\]
\[x_{1} = 4 + 5 = 9;\]
\[x_{2} = 4 - 5 = - 1.\]