Example 19

$\;\;\;(5 + 2p^{3}q)^2$

$=(A + B)^2 \text{, where } A = 5 \text{ and } B = 2p^{3}q $

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

$=(5)^2 + 2(5)(2p^{3}q) + (2p^{3}q)^2 $

$=25 + 20p^{3}q +4p^{6}q^{2} $