$2a^5-32x^4y^4a$

$2a^5-32x^4y^4a$

$2a(a^4-16x^4y^4)$

$2a[(a^2)^2-(4x^2y^2)^2]$

$2a[(a^2+4x^2y^2)(a^2-2x^2y^2)]$

$2a(a^2+4x^2y^2)(a+2xy)(a-2xy)$