Question 976911
Maybe with some commutativity there is one special product to use.


{{{(a-4b+c)(a+4b+c)}}}
{{{(a+c-4b)(a+c+4b)}}}
{{{(a+c)^2-(4b)^2}}}------used Difference of Two Squares Formula
and then
{{{a^2+2ac+c^2-16b^2}}}------included the square binomial