1 câu trả lời
Đáp án:
`sin x - \sqrt{3} cos x = 2 sin 2x`
`=> 1/2 sin x - \sqrt{3}/2 cos x = sin 2x`
`<=> cos \pi/3 . sin x - sin \pi/3 . cos x = sin 2x`
`<=> sin (x - \pi/3) = sin 2x`
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`<=>` $\left[\begin{matrix} x-\frac{\pi}{3}=2x+k2\pi \\ x-\frac{\pi}{3}=\pi-2x+k2\pi\end{matrix}\right.$ `(k in Z)`
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`<=>`$\left[\begin{matrix} x=-\frac{\pi}{3}-k2\pi \\ x=\frac{4\pi}{9}+\frac{k2\pi}{3}\end{matrix}\right.$ `(k in Z)`
