Pt \(\Leftrightarrow\left(2sinx-1\right)\left(2sin2x-1\right)=3-4\left(1-sin^2x\right)\)
\(\Leftrightarrow2sin2x\left(2sinx-1\right)-2sinx+1=-1+4sin^2x\)
\(\Leftrightarrow2sin2x\left(2sinx-1\right)-\left(4sin^2x+2sinx-2\right)=0\)
\(\Leftrightarrow2sin2x\left(2sinx-1\right)-2\left(2sinx-1\right)\left(sinx+1\right)=0\)
\(\Leftrightarrow2\left(2sinx-1\right)\left(sin2x-sinx-1\right)=0\)
\(\Leftrightarrow\left[{}\begin{matrix}sinx=\dfrac{1}{2}\left(1\right)\\sin2x=sinx+1\left(2\right)\end{matrix}\right.\)
Từ (1) \(\Leftrightarrow\left[{}\begin{matrix}x=\dfrac{\pi}{6}+k2\pi\\x=\dfrac{5\pi}{6}+k2\pi\end{matrix}\right.\),\(k\in Z\)
Từ (2)\(\Leftrightarrow2sinx.cosx-sinx-1=0\)
(Cái này tạm thời nghĩ ko ra,tối làm :)
