## Intermediate Algebra (6th Edition)

$(x+2y-3)(x+2y+3)$
Using $a^2-b^2=(a+b)(a-b)$ or the factoring of the difference of two squares, then, \begin{array}{l} (x+2y)^2-9 \\= [(x+2y)-3][(x+2y)+3] \\= (x+2y-3)(x+2y+3) .\end{array}