12x^2 + 3x =0
3x (4x + 1) = 0
3x = 0 ИЛИ 4x + 1 = 0
x = 0 4x = -1
x = -1/4 = - 0,25
Ответ: х1 = 0; х2 = -,025.
Sin(X)sin(2X)-sin(3X) - cos(X)cos(2X) = -(cos(X)cos(2X )- sin(X)sin(2X)) - sin(3X) = - cos(x+2x) - sin(3x) = -(sin3x + cos3x)
3) b²+bc+ab+ac = (b²+ab)+(bc+ac) = b(b+a)+c(b+a) = (b+c)(b+a) при a=-1, b=-2, c=-0,5 , тогда (-2-0,5)(-2-1) = -2,5*(-3) = 7,5
2x-12x-36>=-3
2x-12x>=-3+36
-10x>=-3+36
-10x>=33
x>=-3,3
1)=1-cos^2 t=sin^2 t;
2)=sin^2 t+2 cos^2 t- sin^2t-cos^2t=cos^2t