Answer
$6t^3(3t^2-2t+1)$
Work Step by Step
The $GCF$ of the terms is $
6t^3
$ since it is the highest expression that can evenly divide (no remainder) all the given constants.
Factoring the $GCF,$ the given expression is equivalent to
\begin{array}{l}\require{cancel}
18t^5-12t^4+6t^3
\\\\=
6t^3(3t^2-2t+1)
.\end{array}