| x² + ax | = 4∴ x² + ax = 4 或 x² + ax = - 4即 x² + ax - 4 = 0 或 x² + ax + 4 = 0∵只有三个不相等的实数根且x²+ax-4=0的△恒大于零∴ △ = a² - 16 = 0∴ a = ± 4当 a ...