Question

Решить уровнение
2cos(3x-pi/6)=-1

Answer 1

$2cos(3x-frac{pi}{6})=-1\\cos(3x-frac{pi}{6})=-frac{1}{2}\\3x-frac{pi}{6}=pm (pi -frac{pi}{3})+2pi n=pm frac{2pi}{3}+2pi n,; nin Z\\3x=pm frac{2pi}{3}+frac{pi}{6}+2pi n,; nin Z\\x=pm frac{2pi}{9}+frac{pi}{18}+frac{2pi n}{3}= left [ {{frac{5pi }{18}+frac{2pi n}{3},; nin Z} atop {-frac{pi}{6}+frac{2pi k}{3},; kin Z}} right.$