How do you factor 9x - 64x^3?

We have $9 x - 64 {x}^{3} = f \left(x\right)$
$\implies f \left(x\right) = x \left(9 - 64 {x}^{2}\right)$
$\implies f \left(x\right) = x \left({3}^{2} - {\left(8 x\right)}^{2}\right)$
$\implies f \left(x\right) = x \left(3 + 8 x\right) \left(3 - 8 x\right)$
$9 x - 64 {x}^{3} = x \left(3 + 8 x\right) \left(3 - 8 x\right)$