[tex]\bf 125q^6-r^6 b^2~~ \begin{cases} 125=&5\cdot 5\\ &5^2\\ q^6=&q^{3\cdot 2}\\ &(q^3)^2\\ r^6=&r^{3\cdot 2}\\ &(r^3)^2 \end{cases}\implies 5^2(q^3)^2-(r^3)^2b^2\implies \stackrel{\textit{difference of squares}}{(5q^3)^2-(r^3b)^2} \\\\[-0.35em] \rule{34em}{0.25pt}\\\\ ~\hfill (5q^3-r^3b)(5q^3+r^3 b)~\hfill[/tex]
