Example 41

$\;\;\;(5u - v)^2$

$=(A - B)^2 \text{, where } A = 5u \text{ and } B = v $

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

$=(5u)^2 - 2(5u)(v) + (v)^2 $

$=25u^{2} - 10uv +v^{2} $