Find the solutions of the equation that are in the interval

Find the solutions of the equation that are in the interval [0, 2 pi). (Enter your answers as a comma-separated list. If there is no solution, enter NO SOLUTION.) 12 cos^2 gamma + 6 cos gamma = 0

Solution

12*cos²y + 6*cosy = 0

6*cosy(2*cosy + 1) = 0

cosy = 0 =======> y =  ±/2 + 2k, where k is any integer.======> /2, 3/2

and cosy = -1/2 ======> y = 2/3, 4/3