Decades: 1210s 1220s 1230s 1240s 1250s - 1260s - 1270s 1280s 1290s 1300s 1310s
Years: 1262 1263 1264 1265 1266 - 1267 - 1268 1269 1270 1271 1272
Births
Deaths
... are real. (Geometrically, this means that the parabola intersects the x-axis in two points.) If the discriminant is negative, then there are two different solutions x, ...