Answer:
The product is the difference of squares is [tex]$\left(xy-9\right)\left(xy+9\right)={{x}^2}{{y}^2}-81$[/tex]
Step-by-step explanation:
Explanation
[tex]$\begin{aligned}&(x y-9)(x y+9)=(x y)^{2}-(9)^{2} \\&(x y-9)(x y+9)=x^{2} y^{2}-81\end{aligned}$[/tex]