Answer
$2t^4-11t^2-21$
Work Step by Step
Using $(a+b)(c+d)=ac+ad+bc+bd$ or the product of 2 binomials, the product of the given expression, $
(2t^2+3)(t^2-7)
,$ is
\begin{array}{l}\require{cancel}
2t^2(t^2)+2t^2(-7)+3(t^2)+3(-7)
\\\\=
2t^4-14t^2+3t^2-21
\\\\=
2t^4-11t^2-21
.\end{array}
