Example 64

$\;\;\;(3 - 2xy^{2})^2$

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

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

$=(3)^2 - 2(3)(2xy^{2}) + (2xy^{2})^2 $

$=9 - 12xy^{2} +4x^{2}y^{4} $