4/5➕2/15➕2/45➕2/135➕2/405➕2/1215怎么计算？

解:原式=12/15+2/15+2/45+2/135+2/405
+2/1215
=14/15+2/45+2/135+2/405+2/1215
=42/45+2/45+2/135+2/405+2/1215
=44/45+2/135+2/405+2/1215
=132/135+2/135+2/405+2/1215
=134/135+2/405/2/1215
=402/405+2/405+2/1215
=404/405+2/1215
=1212/1215+2/1215
=1214/1215
或者设原式=s，则
s=4/5+2/15+2/45+2/135+2/405+2/1215……①
3s=12/5+2/5+2/15+2/45+2/135+2/405……②
②一①得:2s=12/5+2/5-4/5-2/1215
s=6/5+1/5-2/5-1/1215
=7/5-2/5-1/1215
=1-1/1215
=1214/1215

温馨提示：答案为网友推荐，仅供参考

当前网址：https://verywind.cn/ee/eej3ey3efryvevj2ee2.html