Решить уравнение 2 cos^2 Пх/3 + 5 sin Пх/3 = 4

2 * (1-sin^2 (πx/3)) + 5sin (πx/3) = 4; - 2sin^2 (πx/3) + 5sin (πx/3) - 2=0

t=sin (πx/3); - 2t+5t-2=0; D=25-4 * (-2) * (-2) = 9=3^2' t1 = (-5-3) / (-4) = 2;

t2 = (-5+3) / (-4) = 0,5

sin (πx/3) = 0,5 ili sin (πx/3) = 2

πx/3 = (-1) ^n (π/6) + πn решений нет

х = (-1) ^n (π/6 * 3/π) + π * (3/π) * n

x = (-1) ^n (0,5) + 3n, n-celoe