Question

решите уравнение 2cosxcosx2x-cosx=0

Answer 1

$2cosx*cos2x-cosx=0\ cosx(2cos2x-1)=0\ cosx=0; 2cos2x-1=0\ cosx=0\ x=frac{pi}{2}+pi n, nin Z\ 2cos2x-1=0\ 2cos2x=1\ cos2x=frac{1}{2}\ 2x=pm frac{pi}{3}+2pi k, k in Z\ x=pm frac{pi}{6}+pi k , kin Z\ \ x=frac{pi}{2}+pi n, nin Z\ x= frac{pi}{6}+pi k , kin Z\ x=- frac{pi}{6}+pi k , kin Z$