Newbie curve fitting question



Hello list,
In learning the first few steps of Maxima, i am trying to find equation
to model some conic sections. i have a model in English like 

at x = 0, y = 0
at x = 10, y = 15
at x = 150, y = 100

Now i want to find some equation to fit this curve, at least to within
some error (like an epsilon for slop, say +/-0.5)

Is this a least mean squares error type fit, and if so, can i get some
part of maxima to assist. i have only the fine manual but it is also
very large.

Any hints appreciated.

Cheers,

Robyn