Решите уравнение: x^4-13x^2+36=0.

\[x^{4} - 13x^{2} + 36 = 0\ \]

\[D = 169 - 144 = 25\]

\[x_{1,2}^{2} = \frac{13 \pm 5}{2}\]

\[x_{1}^{2} = \frac{18}{2} = 9;\ \ \ \ x_{2}^{2} = \frac{8}{2} = 4\]

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