Let me add my five cents to this discussion.
In my opinion user should avoid to use command tex() inside maxima's console
session. There are other beautiful tools to convert maxima result in tex
form. I mean texmacs and emaxima. In texmacs you can easily export results to
latex. For your example you will get after all $7.7850374149\times
10^{12\frac{p}{2}}$. Another benefit is that texmacs can manage multiline
equations.
with best regards,
Valery