Question

Решить неравенство arctgx≥π3
Ответ:
1) [√3/3; +∞)
2) [1; +∞)
3) (−∞; √3/3]
4) [√3; +∞)
5) (−∞; √3]

Answer 1

$arctgx\geq \frac{\pi}{3}\\\\tg(arctgx)\geq tg\frac{\pi}{3}\\\\x\geq \sqrt3\\\\x\in [\, \sqrt3;+\infty )$