1-5/6+7/12-9/20+11/30-13/42+15/56-17/72+19/90简便算法!
问题描述：
1-5/6+7/12-9/20+11/30-13/42+15/56-17/72+19/90
简便算法!
答
可以这样做：
1-5/6+7/12-9/20+11/30-13/42+15/56-17/72+19/90
=1-1/2-1/3+1/3+1/4-1/4-1/5+........+1/9+1/10
=1-1/2+1/10
=1/2+1/10
=5/10+1/10
=6/10
=3/5
我是自己辛辛苦苦打出来的给好评。
答
1-5/6+7/12-9/20+11/30-13/42+15/56-17/72+19/90
=1-(1/2+1/3)+(1/3+1/4)-(1/4+1/5)+(1/5+1/6)-(1/6+1/7)+(1/7+1/8)-(1/8+1/9)+(1/9+1/10)
=1-1/2-1/3+1/3+1/4-1/4-1/5++1/5+1/6-1/6-1/7+1/7+1/8-1/8-1/9+1/9+1/10
=1/2+1/10
=3/5
答
1-5/6+7/12-9/20+11/30-13/42+15/56-17/72+19/90
=1-(1/2+1/3)+(1/3+1/4)-(1/4+1/5)+(1/5+1/6)-(1/6+1/7)+(1/7+1/8)-(1/8+1/9)+(1/9+1/10)
=1-1/2+1/10
=3/5