## Intermediate Algebra (6th Edition)

$4x^2-16y^2$
Using $(a+b)(a-b)=a^2-b^2$ or the product of the sum and difference of like terms, the expression, $(2x-4y)(2x+4y)$, is equivalent to \begin{array}{l} (2x)^2-(4y)^2 \\\\= 4x^2-16y^2 .\end{array}