Example 93

$\;\;\;(11u + 9v^{11})(11u - 9v^{11})$

$=(A + B)( A - B) \text{ , where } A = 11u \text{ and } B = 9v^{11} $

$=A^2-B^2$

$=(11u)^2 - (9v^{11})^2 $

$=121u^{2} - 81v^{22} $