Decades: 1200s 1210s 1220s 1230s 1240s - 1250s - 1260s 1270s 1280s 1290s 1300s
Years: 1250 1251 1252 1253 1254 - 1255 - 1256 1257 1258 1259 1260
Births
Deaths
... to the quadratic equation <math>ax^2+bx+c=0</math> in terms of the coefficients a, b and c, which are assumed to be real (but see below for generalizations) ...