简算 2/3+1/6+1/9+1/12+1/15+1/18

简算 2/3+1/6+1/9+1/12+1/15+1/18
简算 2/3+1/6+1/9+1/12+1/15+1/18

简算 2/3+1/6+1/9+1/12+1/15+1/18
1\3(2+1\2+1\3+1\4+1\5+1\6)=1\3(2+1+1\4+1\5)=1+3\20=23\20

2/3+1/6+1/9+1/12+1/15+1/18
=10/15+1/15+2/12+1/12+1/9+1/18
=11/15+1/4+1/6
=22/30+1/4+5/30
=27/30+1/4
=54/60+15/60
=69/60

原式=2/3+1/3（1/2+1/3+1/4+1/5+1/6）
=2/3+1/3（1+1/4+1/5）
=2/3+1/3（1+9/20）
=2/3+1/3+3/20
=23/20

2/3+1/6+1/9+1/12+1/15+1/18=1/3(2+1/2+1/3+1/4+1/5+1/6)=23/20