\[x^{2}(x + 1) = 9(x + 1)\]
\[x^{2} = 9\ \ \ \ \ \ \ \ \ \ x + 1 = 0\]
\[x = \pm 3\ \ \ \ \ \ \ \ \ x = - 1.\]
\[Ответ:x = \pm 3;\ \ x = - 1.\]