9 A particle moves in the \(x - y\) plane so that at time \(t\) seconds, where \(t \geqslant 0\), its coordinates are given by \(x = \mathrm { e } ^ { 2 t } - 4 \mathrm { e } ^ { t } + 3 , y = 2 \mathrm { e } ^ { - 3 t }\).
- Explain why the path of the particle never crosses the \(x\)-axis.
- Determine the exact values of \(t\) when the path of the particle intersects the \(y\)-axis.
- Show that \(\frac { \mathrm { d } y } { \mathrm {~d} x } = \frac { 3 } { 2 \mathrm { e } ^ { 4 t } - \mathrm { e } ^ { 5 t } }\).
- Hence find the coordinates of the particle when its path is parallel to the \(y\)-axis.