Chapter 6 - Factoring, Solving Equations, and Problem Solving - 6.2 - Factoring the Difference of Two Squares - Problem Set 6.2 - Page 248: 35

$5x(1+2x)(1-2x)$

Factoring out the greatest common factor of 5x, the given expression, $ 5x-20x^3 ,$ is equivalent to \begin{array}{l}\require{cancel} 5x(1-4x^2) .\end{array} Using $a^2-b^2=(a+b)(a-b)$, the completely factored form of the expression above is \begin{array}{l}\require{cancel} 5x(1+2x)(1-2x) .\end{array}