## Intermediate Algebra: Connecting Concepts through Application

$4(3b+2)(3b-2)$
$\bf{\text{Solution Outline:}}$ To factor the given expression, $36b^2-16 ,$ factor first the $GCF.$ Then use the factoring of the sum or difference of $2$ squares. $\bf{\text{Solution Details:}}$ The $GCF$ of the terms is $GCF= 4$ since it is the highest expression that can evenly divide (no remainder) all the given terms. Factoring the $GCF,$ the expression above is equivalent to \begin{array}{l}\require{cancel} 4(9b^2-4) .\end{array} The expressions $9b^2$ and $4$ are both perfect squares (the square root is exact) and are separated by a minus sign. Hence, $9b^2-4 ,$ is a difference of $2$ squares. Using the factoring of the difference of $2$ squares, which is given by $a^2-b^2=(a+b)(a-b),$ the expression above is equivalent to \begin{array}{l}\require{cancel} 4[(3b)^2-(2)^2] \\\\= 4[(3b+2)(3b-2)] \\\\= 4(3b+2)(3b-2) .\end{array}