Example 59

$\;\;\;(3k^{11} - l^{3})^2$

$=(A - B)^2 \text{, where } A = 3k^{11} \text{ and } B = l^{3} $

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

$=(3k^{11})^2 - 2(3k^{11})(l^{3}) + (l^{3})^2 $

$=9k^{22} - 6k^{11}l^{3} +l^{6} $