Duccius[?] - inscriptions, notably a tombstone of Lucius Duccius Rufinus at York[2] (http://museums.ncl.ac.uk/archive/arma/contents/iconog/tombston/cent1/uk/york/duccius.htm)
... is equivalent to
<math>x^2+\frac{b}{a}x=-\frac{c}{a}.</math>
The equation is now in a form in which we can conveniently complete the square[?]. ...