Question

sin^2x - 2 cos2x = - 2

Answer 1

sin^2x - 2 cos2x = - 2
sin^2x - 2 ( 1 - 2sin^2x ) + 2 = 0
sin^2x - 2 + 4sin^2x + 2 = 0
5sin^2x = 0
sin^2x = 0
sinx = 0
x = pik, k ∈ Z

Answer 2

Вроде так:)

sin^2x - 2 cos2x = - 2
sin^2x - 2 * (1 - 2sin^2x) = - 2
sin^2x - 2  + 4 * sin^2x = - 2
sin^2x + 4 * sin^2x = 0
sin^2x * (1+4) = 0
5 * sin^2x = 0
sin^2x = 0
sinx        *       sinx =0
x = pi*n   при n принадлежащим Z