ECUACIONES TRIGONOMETRICASCos2x = cos x?

<img src="https://tex.z-dn.net/?f=%20%5Ccos%282x%29%3D%5Ccos%20x%5C%5C%20%5C%5C%202%5Ccos%5E2x-1%3D%5Ccos%20x%20%5Chspace%7B2.2cm%7D%5Ctext%7B%28coseno%20del%20%5C%27angulo%20doble%29%7D%5C%5C%20%5C%5C%202%5Ccos%5E2x-%5Ccos%20x-1%3D0%5C%5C%5C%5C%20%282%5Ccos%20x%20%2B1%29%28%5Ccos%20x%20-1%29%3D0%5Chspace%7B1cm%7D%5Ctext%7B%28factorizaci%5C%27on%29%7D%5C%5C%20%5C%5C%20%5Ccos%20x%20%3D-%5Cdfrac%7B1%7D%7B2%7D%20%5Cvee%20%5Ccos%20x%20%3D%201%5C%5C%20%5C%5C%20x_%7B1%2Cp%7D%3D%5Cdfrac%7B2%5Cpi%7D%7B3%7D%5Cvee%20x_%7B2%2Cp%7D%3D0%5Chspace%7B2cm%7D%5Ctext%7B%28soluciones%20principales%29%7D%5C%5C%20%5C%5C%20X_1%3D2%5Cpi%20k_1%5Cpm%20%5Cdfrac%7B2%5Cpi%7D%7B3%7D%5Cvee%20X_2%3D2%5Cpi%20k_2%5Chspace%7B0.6cm%7D%5Ctext%7B%28soluciones%20generales%29%7D%20" />Conjunto solución : <img src="https://tex.z-dn.net/?f=%20x%5Cin%5Cleft%5C%7B2%5Cpi%20k%5Cpm%20%5Cdfrac%7B2%5Cpi%7D%7B3%7D%2C2%5Cpi%20k~%5Cleft%7C%5Cdfrac%7B%7D%7B%7D%20%5Cright.~k%5Cin%5Cmathbb%7BZ%7D%5Cright%5C%7D%20" />.