Example 119

$\;\;\;(3x + 2y^{5})(3x - 2y^{5})$

$=(A + B)( A - B) \text{ , where } A = 3x \text{ and } B = 2y^{5} $

$=A^2-B^2$

$=(3x)^2 - (2y^{5})^2 $

$=9x^{2} - 4y^{10} $