Chapter 5 - Sections 5.1-5.7 - Integrated Review - Operations on Polynomials and Factoring Strategies - Page 313: 15

$4(x+2)(x-2)$

Factoring the $GCF=4$, then the given expression, $ 4x^2-16 $, is \begin{array}{l} 4(x^2-4) .\end{array}Using $a^2-b^2=(a+b)(a-b)$ or the factoring of the difference of 2 squares, then the factored form of the expression, $ 4(x^2-4) $, is \begin{array}{l} 4(x+2)(x-2) .\end{array}