Giải thích các bước giải:
$\dfrac{a}{2016}=\dfrac{b}{2017}=\dfrac{c}{2018}=\dfrac{a-c}{2016-2018}=\dfrac{a-b}{2016-2017}=\dfrac{b-c}{2017-2018}$
$\rightarrow \dfrac{a-c}{-2}=\dfrac{a-b}{-1}=\dfrac{b-c}{-1}$
$\rightarrow a-c=2(a-b)=2(b-c)$
$\rightarrow (a-c)^3=(2(a-b))^2.2(b-c)$
$\rightarrow (a-c)^3=8(a-b)^2(b-c)\rightarrow đpcm$