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)
... formula reads
<math>
x=\frac{-b \pm \sqrt {b^2-4ac}}{2a}
</math>
The term b2 – 4ac is called the discriminant of the quadratic equation, because ...