\[Пусть\ t = x^{2} + 4x - 4:\]
\[t^{2} - 9t + 8 = 0\]
\[t_{1} + t_{2} = 9\]
\[t_{1} \cdot t_{2} = 8\]
\[\Longrightarrow t_{1} = 8,\ \ t_{2} = 1.\]
\[Ответ:\ x = - 6;x = 2;\ x = - 5;\]
\[x = 1.\]