Chứng minh với $\it{x}> \it{0}$$:$
$$\it{\lambda}\leqq \frac{\it{12}\,\it{x}^{\,\it{3}}- \it{22}\,\it{x}^{\,\it{2}}+ \it{20}\,\it{x}- \it{2}\it{(}\,\,\it{x}+ \it{2}\,\,\it{)}\sqrt{\it{(}\,\,\it{4}- \it{x}^{\,\it{2}}\,\,\it{)}\it{(}\,\,\it{1}+ \it{2}\,\it{x}^{\,\it{2}}\,\,\it{)}}+ \it{8}}{\it{x}\it{(}\,\,\it{x}- \it{1}\,\,\it{)}^{\,\it{2}}}$$
$$\Updownarrow$$
$$\it{\lambda}\leqq \it{16}$$