Question

Алгебра ....тригонометрия хээлп

Answer 1

$5cosx+cos2x+3 geq 0\\5cosx+(2cos^2x-1)+3 geq 0\\2cos^2x+5cosx+2 geq 0; ,; ; -1 leq cosx leq 1\\D=25-16=9; ,\\(cosx)_1= frac{-5-3}{4} =-2 textless -1; ; ne podxodit\\(cosx)_2= frac{-5+3}{4} =-frac{1}{2}\\x=pm arccos(-frac{1}{2})+2pi n; ,; nin Z\\x=pm (pi-frac{pi}{3})+2pi n=pm frac{2pi}{3}+2pi n,; nin Z$