№16
4Sin²x -5SinxCosx - Cos²x = 2*1
4Sin²x -5SinxCosx - Cos²x = 2*(Sin²x + Cos²x)
4Sin²x -5SinxCosx - Cos²x = 2Sin²x + 2Cos²x
2Sin²x -5SinxCosx -3Cos²x = 0 | : Cos²x
2tg²x - 5tgx -3 = 0
D = 25 -4*2*(-3) = 25 + 24 = 49
tgx = 3 tgx = -0,5
x = arctg3 + πk , k ∈Z x = -arctg0,5 + πn , n ∈Z