Chapter 5 - Section 5.3 - Special Products - Exercise Set - Page 368: 54

$25x^4-30x^2+9$

Using $(a\pm b)^2=a^2\pm2ab+b^2$ or the square of a binomial, the square of the given expression, $( 5x^2-3 )^2,$ is \begin{array}{l}\require{cancel} (5x^2)^2-2(5x^2)(3)+(3)^2 \\\\= 25x^4-30x^2+9 .\end{array}