Решите уравнение: x^4-26x^2+25=0.

\[x^{4} - 26x^{2} + 25 = 0\]

\[x^{4} - x^{2} - 25x^{2} + 25 = 0\]

\[x^{2}\left( x^{2} - 1 \right) - 25\left( x^{2} - 1 \right) = 0\]

\[\left( x^{2} - 1 \right)\left( x^{2} - 25 \right) = 0\]

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

\[x = \pm 1.\]

\[2)\ x^{2} = 25\]

\[x = \pm 5.\]

\[Ответ:x = \pm 1;\ \ x = \pm 5.\]