Question

•Решите неравенство Заранее спасибо Ctg(-7x)≥-1

Answer 1

$ctg(-7x) \geq -1\\-ctg7x \geq -1\\ctg7x \leq 1\\\ \pi n \ \textless \ 7x \leq \frac{\pi}{4}+\pi n\\\frac{\pi n}{7}\ \textless \ x \leq \frac{\pi}{28}+\frac{\pi n}{7}, \; n \in Z$