3cos²2x - 5sin²x - sin2x = 0
5sin²x + sin2x - 3cos²x = 0
5sin²x + 2sinxcosx - 3cos²x = 0 |:cos²x
5tg²x + 2tgx - 3 = 0
5tg²x + 5tgx - 3tgx - 3 = 0
5tgx(tgx + 1) - 3(tgx + 1) = 0
(5tgx - 3)(tgx + 1) = 0
1) 5tgx - 3 = 0
5tgx = 3
tgx = 3/5
x = arctg(3/5) + πn, n ∈ Z
2) tgx + 1 = 0
tgx = -1
x = -π/4 + πk, k ∈ Z
Ответ: x = arctg(3/5) + πn, n ∈ Z; -π/4 + πk, k ∈ Z.
а(б+с-бс)-б(с+а-ас)+с(б-а)= аб+ас-абс-бс-ба+абс+сб-са=0
A) 36x²-1 -36x²-8x = -1
-1 -8x= -1
8x= -1+1
8x=0
x=0
b) 8a -9a²= -40 +36 -9a²
8a -9a² +9a² = -4
8a= -4
a= -4/8= -0.5
(x +5)^2 - (x-11)^2 = 128
x^2 +10x +25 -x^2 +22x - 121 =128
32x =128 -25 +121
32x = 224
x = 7