\[x^{4} - 29x^{2} + 100 = 0\]
\[Пусть\ x^{2} = y \geq 0:\]
\[y^{2} - 29y + 100 = 0\]
\[y_{1} + y_{2} = 29;\ \ y_{1} \cdot y_{2} = 100\]
\[y_{1} = 25;\ \ y_{2} = 4\]
\[Подставим:\]
\[1)\ y = 25:\]
\[x^{2} = 25\]
\[x = \pm 5.\]
\[2)\ y = 4:\]
\[x^{2} = 4\]
\[x = \pm 2.\]
\[Ответ:\ \ x = \pm 2;\ \ x = \pm 5.\]