## Introductory Algebra for College Students (7th Edition)

$x^2y^2-6xy+9$
Using $(a\pm b)^2=a^2\pm2ab+b^2$ or the square of a binomial, the square of the given expression, $(xy-3)^2 ,$ is \begin{array}{l}\require{cancel} (xy)^2-2(xy)(3)+(3)^2 \\\\= x^2y^2-6xy+9 .\end{array}