What can you say about the (Liapunov) stability of the zero solution of the following system?

$\displaystyle \left\{\begin{array}{l}x'_1=e^{-t}x_1^3-x_2\\\\\displaystyle x'_2=\frac{t^2}{1+t^2}x_1+\alpha x_2\end{array}\right\}$

???

First of all, what the heck is the "zero solution"?

Second, does anyone know how to answer this? I don't even know where to start. If it were a linear system then I'd convert to a first-order vector form, but it's not, so I can't.

Any help would be much appreciated!