Example 58

$\;\;\;(2k^{4} - l^{4})^2$

$=(A - B)^2 \text{, where } A = 2k^{4} \text{ and } B = l^{4} $

$=A^2 - 2AB + B^2$

$=(2k^{4})^2 - 2(2k^{4})(l^{4}) + (l^{4})^2 $

$=4k^{8} - 4k^{4}l^{4} +l^{8} $