Centuries: 12th century - 13th century - 14th century
Decades: 1220s 1230s 1240s 1250s 1260s - 1270s - 1280s 1290s 1300s 1310s 1320s
Years: 1270 1271 1272 1273 1274 1275 1276 1277 1278 1279
... quadratic formula is derived by the method of completing the square[?]. <math>ax^2+bx+c=0</math> Dividing our quadratic equation by a, w ...