Factorize each of the following expression:

$a^{4}-(2 b+c)^{4}$

$=\left(a^{2}\right)^{2}-\left[(2 b+c)^{2}\right]^{2}$

$=\left[a^{2}+(2 b+c)^{2}\right]\left[a^{2}-(2 b+c)^{2}\right]$

$=\left[a^{2}+(2 b+c)^{2}\right]\{[a+(2 b+c)][a-(2 b+c)]\}$

$=\left[a^{2}+(2 b+c)^{2}\right](a+2 b+c)(a-2 b-c)$