Introductory Algebra for College Students (7th Edition)

$x^{24}-9$
Using $(a+b)(a-b)=a^2-b^2$ or the special product of the sum and difference of like terms, the product of the given expression, $(x^{12}+3)(x^{12}-3) ,$ is \begin{array}{l}\require{cancel} x^{12}(x^{12})-3(3) \\\\= x^{24}-9 .\end{array}