Factorize:

$x-8 x y^{3}=x\left(1-8 y^{3}\right)$

$=x\left[1^{3}-(2 y)^{3}\right]$

$=x(1-2 y)\left(1^{2}+1 \times 2 y+(2 y)^{2}\right)$

$=x(1-2 y)\left(1+2 y+4 y^{2}\right)$