Sorry everyone - posted the above too quickly
I think solution is
A = a
B = by + d
Peter
An early exercise in the book Algebraic Geometry by Thomas Garrity et. al. is the following:
Exercise 1.1.13. Express the polynomial in the form
where A, B and C are polynomials in y. What are A, B and C?
I would appreciate some help with this problem.
Peter