Decades: 1230s 1240s 1250s 1260s 1270s - 1280s - 1290s 1300s 1310s 1320s 1330s
Years: 1283 1284 1285 1286 1287 - 1288 - 1289 1290 1291 1292 1293
Births
Deaths
... the usual form of the quadratic formula is not ideal. See Loss of significance for details. Derivation The quadratic formula is derived by the method of completing the ...