[tex]\bf \textit{difference of squares} \\\\ (a-b)(a+b) = a^2-b^2 \\\\[-0.35em] \rule{34em}{0.25pt}\\\\ 64x^2-25y^2~~ \begin{cases} 64=8\cdot 8\\ \qquad 8^2\\ 25=5\cdot 5\\ \qquad 5^2 \end{cases}\implies 8^2x^2-5^2y^2\implies (8x)^2-(5y)^2 \\\\[-0.35em] \rule{34em}{0.25pt}\\\\ ~\hfill (8x-5y)(8x+5y)~\hfill[/tex]
