Hi guys. I'd like to solve the following:

This corresponds to the problem .,

.

Then the characteristic equations are given by

, , , , .

And it's easy to find the curves (there are two) induced by the initial condition:

Solving for we have

(where the signs correspond to the signs in ).

But I don't know how to put this in closed form (i.e. in the form ). It may just be a simple elementary calculus/algebra block on my part. Any help would be much appreciated!