## Elementary and Intermediate Algebra: Concepts & Applications (6th Edition)

$(t^2+3)(t^2-3)$
Using $a^2-b^2=(a+b)(a-b)$ or the factoring of the difference of $2$ squares, then the factored form of the given expression, $t^4-9$, is \begin{array}{l} (t^2+3)(t^2-3) .\end{array}