Answer
$2(7t+3)(7t-3)$
Work Step by Step
Factoring the $GCF=
2
$, then the given expression, $
98t^2-18
$ is equivalent to
\begin{array}{l}
2(49t^2-9)
.\end{array}
Using $a^2-b^2=(a+b)(a-b)$ or the factoring of the difference of $2$ squares, then the complete factored form of the expression above is
\begin{array}{l}
2(7t+3)(7t-3)
.\end{array}