\[x^{2} - 4x - 5 \leq 0\]
\[D_{1} = 4 + 5 = 9\]
\[x_{1} = 2 + 3 = 5;\]
\[x_{2} = 2 - 3 = - 1;\]
\[(x + 1)(x - 5) \leq 0\]
\[- 1 \leq x \leq 5.\]
\[Ответ:\ - 1 \leq x \leq 5.\]