$pt<=>(2sinx-1)(-4sin^2x+2sinx+3)=4sin^2x-1$$<=>(2sinx-1)(-4sin^2x+2sinx+3)=(2sinx+1)(2sinx-1)$$<=>(2sinx+1)(4sin^2x-2)=0$$Xong$
$pt<=>(2sinx-1)
[2(1-2sin^2x)+2sinx+1]=3-4(1-sin^2x)$$<=>(2sinx-1)(-4sin^2x+2sinx+3)=4sin^2x-1$$<=>(2sinx-1)(-4sin^2x+2sinx+3)=(2sinx+1)(2sinx-1)$$<=>(2sinx+1)(4sin^2x-2)=0$$Xong$