6cos² 2x+22sin²x-7=0
6(1 - 2Sin²x)²+22sin²x-7=0
6(1 -4Sin²z +4Sin⁴x) +22Sin²x -7 = 0
6 -24Sin²x + 246Sin⁴x +22Sin²x -7=0
24Sin⁴x -2Sin²x -1 = 0
Sin²x = t
24t² -2t -1 = 0
t = (1+-√(1 +24))/24 = (1 +-5)/24
t₁=1/4, t₂= -1/6
Sin²x = 1/4 Sin²x = -1/6
Sinx = +-1/2 ∅
x = (-1)^narcSin(+-1/2) + nπ