3)
а)tq²x +tqx =0 ;
tqx(tqx+1) =0 ;
[tqx =0 ; tqx =-1 . [x =π*k ; x =-π/4 + π*k ,k∈Z.
б) cos4x -cos2x +sin3x =0;
- 2sin3xsinx +sin3x= 0;
-2sin3x(sinx -1/2) =0 ;
[sin3x=0 ; sinx=1/2. [x =π/3*k ; x=(-1)^(k)*π/3 + π*k ,k∈Z.
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4) sin3x +√3cos3x =1 ;
√3/2cos3x +1/2*sin3x =1/2;
cosπ/6*cos3x +sinπ/6*sin3x =1/2 ;
cos(x -π/6) =1/2;
x -π/6 =(+/-)π/3 +2π*k ,k∈Z.
x = π/6 +(+/-)π/3 +2π*k ,k∈Z.
или иначе
[ x =π/2 +2π*k ; x = -π/6+2π*k,k∈Z.