[latex]cos 10x-cos 8x-cos 6x+1=0[/latex]

[latex]cos2x+cos6x=1+cos8x\\ 2cos4xcos2x=2cos^24x\\ cos4x(cos2x-cos4x)=0\\ cos4x*2sin3x*sinx=0\\ \left[ \begin{matrix} cos4x=0 \\ sin3x=0 \\ sin\ x=0 \end{matrix}\right. <=> \left[ \begin{matrix} 4x=\frac{\pi}{2}+\pi k \\ 3x=\pi n \\ x=\pi m \end{matrix}\right. <=> \left[ \begin{matrix} x=\frac{\pi}{8}+\frac{\pi k}{4} \\ x=\frac{\pi n}{3} \\ x=\pi m \end{matrix}\right. \\\\ Ombem:\ \frac{\pi}{8}+\frac{\pi k}{4};\ \frac{\pi n}{3};\ \pi m;\ k,n,m \in Z.[/latex]