Question

6cos^2x+5cosx+1=0

 

Answer 1

$6cos^2x+5cosx+1=0 \ cosx=y \ 6y^2+5y+1=0 \ D=25-24=1 \ y_1=frac{-5+1}{12}=-frac{1}{3} \ y_2=frac{-5-1}{12}=-0,5 \ cosx=-frac{1}{3} \ x_1=бarccos(-frac{1}{3})+2pi*n \ cosx=-0,5 \ x_2=бfrac{2pi}{3}+2pi*n$