x = \( \sqrt[4]{\frac{-3b^2}{12a^2} + \frac{c}{3a}} + \sqrt[4]{\frac{3b^2}{12a^2} - \frac{c}{3a}} + \frac{b}{4a} \left(\sqrt[4]{\frac{-3b^2}{12a^2} + \frac{c}{3a}} - \sqrt[4]{\frac{3b^2}{12a^2} - \frac{c}{3a}}\right) \)