linsolve strange behavior



RJF,

> On commercial macsyma, I get for the first problem,...
> I then ran the first problem on maxima 5.9.0 and it got the 
> same answer.

Commercial Macsyma is getting the correct answer.  Maxima 5.9.0 on my
machine (GCL, W2k) is not getting the same answer; it has DX where it
should have coeff_y, which is not correct.  What is your 5.9.0
configuration?

I tested without the assumes, which as you say are not used by solve.

       -s