giúp vs

Question

$3sin^2(x)+cos^2(x)+sin(2x)-cos(x)-3sin(x)=0$

score 1 · Answer 1

$3sin^{2} x + \cos ^{2}x + sin 2x - 3sinx -cosx = 0 $

$0= 1 + 2sin^{2}x + 2 sinxcosx -cosx -3sinx$

$= (2sin^{2}x -sinx)+(2sinxcosx-cosx)-(2sinx-1) $

$=sinx(2sinx-1)+cosx(2sinx-1)-(2sinx-1)$

$=(2sinx-1)(cosx+sinx -1)$

$TH1: sinx=1/2 $

$TH2:Sin(x+\frac{\pi }{4})=1/\sqrt{2}$

score 2 · Answer 2

$3sin^2x+cos^2x+sin2x-cosx-3sinx=0$

$\Leftrightarrow 2\sin^2 x -3\sin x +1 + \cos x(2\sin x -1) = 0$

$\Leftrightarrow (2\sin x -1)(\sin x -1) + \cos x (2\sin x -1) =0$ dễ rồi tự làm

2 Đáp án