# Find the first $5$ terms of the sequence whose general term is $t_n=(-1)^{n-1}.\:5^{n+1}$
$\begin{array}{1 1}25,125,625,3125,15625 \\25,-125,625,3125,15625 \\ 25,125,625,-3125,15625 \\ 25,-125,625,-3125,15625 \end{array}$