PT $\Leftrightarrow 4\sin x\cos x+2\sin ^{2}x-1-7\sin x-2\cos x+4=0$$\Leftrightarrow 2\cos x(2\sin x-1)+(2\sin x-1)(\sin x-3)=0$$\Leftrightarrow (2\sin x-1)(2\cos x+\sin x-3)=0$$\sin x=0,5\Rightarrow x=\frac{\pi }{6}+2k\pi , or x=\frac{5\pi }{6}+2k\pi .$hoặc :$2\cos x+\sin x=3\Leftrightarrow $(vô nghiệm vì $3>\sqrt{4+1})$kl
PT $\Leftrightarrow 4\sin x\cos x+2\sin ^{2}x-1-7\sin x-2\cos x+4=0$$\Leftrightarrow 2\cos x(2\sin x-1)+(2\sin x-1)(\sin x-3)=0$$\Leftrightarrow (2\sin x-1)(2\cos x+\sin x-3)=0$$\sin x=0,5\Rightarrow x=\frac{\pi }{6}+2k\pi , or x=\frac{5\pi }{6}=2k\pi .$hoặc :$2\cos x+\sin x=3\Leftrightarrow $(vô nghiệm vì $3>\sqrt{4+1})$kl
PT $\Leftrightarrow 4\sin x\cos x+2\sin ^{2}x-1-7\sin x-2\cos x+4=0$$\Leftrightarrow 2\cos x(2\sin x-1)+(2\sin x-1)(\sin x-3)=0$$\Leftrightarrow (2\sin x-1)(2\cos x+\sin x-3)=0$$\sin x=0,5\Rightarrow x=\frac{\pi }{6}+2k\pi , or x=\frac{5\pi }{6}
+2k\pi .$hoặc :$2\cos x+\sin x=3\Leftrightarrow $(vô nghiệm vì $3>\sqrt{4+1})$kl