Example 18

$\;\;\;(7k^{5} + 12l^{10})^2$

$=(A + B)^2 \text{, where } A = 7k^{5} \text{ and } B = 12l^{10} $

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

$=(7k^{5})^2 + 2(7k^{5})(12l^{10}) + (12l^{10})^2 $

$=49k^{10} + 168k^{5}l^{10} +144l^{20} $