Question

решите уравнение
6sin^2 x-cosx-5=0

Answer 1

6(1 - Cos²x) - Cosx - 5 = 0
6 - 6Cos²x - Cosx -5 = 0
6Cos²x + Cosx -1 = 0
D = 25
Cosx = (-1+5)/12= 1/3                      б) Cosx = (-1 -5)/12 = -1/2
x = +-arcCos1/3 + 2πk, k ∈Z                   x = +-2π/3+ 2πn, n ∈Z