Решите уравнение: x^4-5x^2+4=0

\[x^{4} - 5x^{2} + 4 = 0\]

\[x^{4} - x^{2} - 4x^{2} + 4 = 0\]

\[x^{2}\left( x^{2} - 1 \right) - 4\left( x^{2} - 1 \right) = 0\]

\[\left( x^{2} - 1 \right)\left( x^{2} - 4 \right) = 0\]

\[1)\ x^{2} = 1\]

\[x = \pm 1.\]

\[2)\ x^{2} = 4\]

\[x = \pm 2.\]

\[Ответ:x = \pm 1;x = \pm 2.\]