Решите уравнение: x^4-10x^2+9=0.

\[x^{4} - 10x^{2} + 9 = 0\ \]

\[D = 100 - 36 = 64\]

\[\text{x\ }_{1,2}^{2} = \frac{10 \pm 8}{2}\]

\[x_{1}^{2} = \frac{2}{2} = 1;\ \ \ \ x_{2}^{2} = \frac{18}{2} = 9\]

\[x_{1} = \pm 1\ \ \ \ \ \ \ \ \ \ x_{2} = \pm 3\]