## Intermediate Algebra (12th Edition)

$(y+z+9)(y+z-9)$
$\bf{\text{Solution Outline:}}$ To factor the given expression, $(y+z)^2-81 ,$ use the factoring of the difference of $2$ squares. $\bf{\text{Solution Details:}}$ Using $a^2-b^2=(a+b)(a-b)$ or the factoring of the difference of $2$ squares, the factored form of the expression above is \begin{array}{l}\require{cancel} [(y+z)+9][(y+z)-9] \\\\= (y+z+9)(y+z-9) .\end{array}