Decades: 1210s 1220s 1230s 1240s 1250s - 1260s - 1270s 1280s 1290s 1300s 1310s
Years: 1262 1263 1264 1265 1266 - 1267 - 1268 1269 1270 1271 1272
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... x + \frac{c}{a}=0 </math> which is equivalent to <math>x^2+\frac{b}{a}x=-\frac{c}{a}.</math> The equation is now in a form in which we ca ...