Question

очень  срочно!!
3cos^2пx+4cosпx-7=0

Answer 1

$3cos^{2} pi x+4cos pi x-7=0\cos pi x=t\3t^{2}+4t-7=0\D=16+84=100\t_{1}=1\t_{ 2}=- frac{7}{3}\cos pi x neq - frac{7}{3} \ cos pi x=1\ pi x= pi +2 pi n\x=1+2n$