2sin3x -2sinxcosx-sin5x=0 giup mk voi cam on bang ca tam long

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1. Giải thích các bước giải:

   $2\sin 3x-2\sin x\cos x-\sin 5x=0$

   $\rightarrow 2\sin 3x=\sin 2x+\sin 5x$ 

   $\rightarrow 2\sin 3x=2\sin \dfrac{7x}{2}\cos \dfrac{3x}{2}$ 

   $\rightarrow \sin 3x=\sin \dfrac{7x}{2}\cos \dfrac{3x}{2}$ 

   $\rightarrow  2\sin \dfrac{3x}{2}\cos \dfrac{3x}{2}=\sin \dfrac{7x}{2}\cos \dfrac{3x}{2}$ 

   $\rightarrow\cos \dfrac{3x}{2}(  2\sin \dfrac{3x}{2}-\sin \dfrac{7x}{2})=0$ 

   $+)\cos \dfrac{3x}{2}=0\rightarrow x=\dfrac{\pi}{3}+\dfrac{4k\pi}{3}, x=\pi+\dfrac{4k\pi}{3}$

   $+) 2\sin \dfrac{3x}{2}-\sin \dfrac{7x}{2}=0$

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