\[y = x^{4} - 3x^{2} - 4\]
\[y = 0:\]
\[x^{4} - 3x^{2} - 4 = 0\]
\[Пусть\ x^{2} = a \geq 0:\]
\[a^{2} - 3a - 4 = 0\]
\[a_{1} + a_{2} = 3;\ \ \ a_{1} \cdot a_{2} = - 4\]
\[a_{1} = - 1;\ \ \ \ a_{2} = 4.\]
\[Подставим:\]
\[x^{2} = 4\]
\[x = \pm 2.\]
\[Ответ:( - 2;0)\ и\ (2;0).\]