Answer
$y(y^{2}+4)(y+2)(y-2)$
Work Step by Step
$y^{5}-16y=$
factor out the GCF, $y$
$=y(y^{4}-16)$
The parentheses hold a difference of squares,
$=y[(y^{2})^{2}-4^{2})$
$=y(y^{2}+4)(y^{2}-4)$
The last parentheses hold a difference of squares,
$=y(y^{2}+4)(y+2)(y-2)$
