> Quite clear, I believe.
> Just one more question: Anyhow, Ferrari was a disciple of Cardano, and
> there are reports that he (Ludovico) was, since fourteen years old, a
> servant in Cardano's house. Do you think that his testimony may have
> been biased?
Interesting question, but... Cardano's own comments suggest that Ferrari
is the the one who did most of the work, including extension to fourth
degree. That introduces a different sort of bias entirely.
Calling Cardano's computations "the solution for all types of cubic
equations" is also tenuous, considering the problems with negatives. The
method still works, but Cardano was *clearly* baffled.
VS-)