$a\geqq b\geqq c$
$$\therefore\,1\geqq 2(\,a- b\,)(\,b- c\,)(\,\frac{\,\,\,\,\,\,3}{\sqrt[3\,]{2}}\times c- a\,)$$
$a\geqq b\geqq c$
$$\therefore\,1\geqq 2(\,a- b\,)(\,b- c\,)(\,\frac{\,\,\,\,\,\,3}{\sqrt[3\,]{2}}\times c- a\,)$$
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