4) $$tg 2x = - \sqrt{3}$$

Решим уравнение $$tg 2x = - \sqrt{3}$$. $$2x = arctg(-\sqrt{3}) + \pi n, n \in Z$$ $$2x = -\frac{\pi}{3} + \pi n, n \in Z$$ $$x = -\frac{\pi}{6} + \frac{\pi n}{2}, n \in Z$$ Ответ: $$x = -\frac{\pi}{6} + \frac{\pi n}{2}, n \in Z$$