3 SIN2X+COS2X=2COSX-1Û 2 3SINXCOSX + 2COS2X = 2COSX Û COSX = 0...
Câu 2. 3 sin2x+cos2x=2cosx-1Û 2 3sinxcosx + 2cos
2
x = 2cosx Û cosx = 0 hay 3sinx + cosx = 113x 2 cosx =3 32 sinx + 2 Û cosx = 0 hay cos( ) cosÛ cosx = 0 hay 2 2 x 3 k2 k hay x kÛ x = 2 hay