Quadratic Surface of Best Fit

I have a set of a few hundred points that lie on a quadratic. My first thought was to use least squares to solve

Ax^2 + By^2 + Cz^2 + Dxy + Fyz + Gxz + Hx + Jy + Kz + L = 0

setting the values of b (Ax = b) to z and filling in the A matrix with the rest of the data. However I don’t know how implement the surface given by the formula in OpenGL.