\[x^{3} + 6x^{2} - x - 6 = 0\]
\[x^{2}(x + 6) - (x + 6) = 0\]
\[(x + 6)\left( x^{2} - 1 \right) = 0\]
\[1)\ x + 6 = 0\]
\[x = - 6.\]
\[2)\ x^{2} - 1 = 0\]
\[x^{2} = 1\]
\[x = \pm 1.\]
\[Ответ:x = - 6;\ \ x = \pm 1.\]