G i ả i p h ư ơ n g t r ì n h v ớ i $0\leqq w< 2\,\pi$
$$\begin{equation}\begin{split} 2\,\sqrt{\,2}(\,\sin^{\,3}\,w+ \cos^{\,3}\,w\,)+ 3\,\sin\,w\,\cos\,w= 0 \end{split}\end{equation}$$
$\Leftrightarrow 2\sqrt{2}\left ( sinx+cosx \right )\left ( sin^2x-sinx.cosx+cos^2x \right ) +3sinxx.cosx=0$
đặt $ t=sinx + cosx$ suy ra $\left | t \right |\leq \sqrt{2} và sinx.cosx=\frac{t^2-1}{2}$
$ \Rightarrow2\sqrt{2} t(\frac{-t^2+1}{2}+1) +3\frac{t^2-1}{}2 =0$