Determine the general solution for $2\cos 2x−5\cos x+2=0$ Determine the general solution for $2\cos 2x−5\cos x +2=0$
my answer I got was : $1.05+n\pi, 4.19+n\pi$

$$\implies 2(2\cos^2x-1)-5\cos x+2=0\iff \cos x(4\cos x-5) =0$$
If $\cos x=0,x =\frac{(2m+1)\pi}2$ where $m$ is any integer
If $4\cos x-5=0, \cos x=\frac54>1$ but  for real $x, -1\le \cos x\le 1$
