$\begin{array}{|c|c|c|c|c|} \hline t( s ) & 0 & 1 & 2 & 3 \\ \hline x ( m ) & -2 & 0 & 6 & 16 \\ \hline \end{array} $
By using the data from the table
\({v_1} = \frac{{0 - ( - 2)}}{1} = 2\,m/s\)
\({v_2} = \frac{{6 - 0}}{1} = 6\;m/s\)
\({v_3} = \frac{{16 - 6}}{1} = 10\;m/s\)
So, motion is non-uniform but accelerated.