Example 115

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

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

$=A^2-B^2$

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

$=4 - 25x^{4}y^{6} $