## Precalculus (6th Edition) Blitzer

$(8x-9)(8x+9)$
The given expression can be written as $(8x)^2-9^2.$ The expression above is a difference of two squares. RECALL: $a^2-b^2=(a-b)(a+b).$ Factor the difference of two squares using the formula above to obtain $(8x-9)(8x+9).$