Câu d)$\Leftrightarrow 1+(sin2x + cos2x)(1-sin2x.cos2x)= 3sin2x.cos2x$Đặt $sin2x + cos2x = t (-2<t<2) \Rightarrow sin2x.cos2x = \frac{t^2 - 1}{2}$Có: $1+ t(1-\frac{t^2-1}2)=3\frac{t^2-1}2$Giải t rồi suy ra x
Câu d)$\Leftrightarrow 1+
\left(
\sin2x+
\cos2x
\right)
\left(1-
\sin2x
\cos2x
\right)=3
\sin2x
\cos2x$Đặt $
\sin2x+
\cos2x=t
,\,\,\left(-2<t<2
\right)\Rightarrow
\sin2x
\cos2x=\
dfrac{t^2-1}{2}$Có: $1+ t
\left(1-\
dfrac{t^2-1}2
\right)=3\
times\frac{t^2-1}2$Giải
$t
$ rồi suy ra
$x
.$