{\mathbf{Y}}\left( t \right) = \left[ {\begin{array}{*{20}c}
 { - 7e^t + 7e^{2t} - 4te^t } \\
 { - 2e^t + 2e^{2t} } \\
 {e^{2t} } \\

 \end{array} } \right]