Bruttius Balbus, a candidate for duovir[?] of Pompeii, mentioned in political graffiti (from Walls of Pompeii (http://www.cis.vt.edu/fac/thb/1124/wallsofpompeii))
... field of characteristic 2, the element 2a is zero and it is impossible to divide by it.)
The symbol
<math>\pm \sqrt {b^2-4ac}</math>
in the formula ...