1/3+1/6+1/10+1/15+1/21+```````+1/105+1/120
1/3+1/6+1/10+1/15+1/21+1/28+1/36+1/45+1/55+1/66
1\3+1\6+1\10+1\15+1\21+1\28+1\36+1\45+1\50+1\55
1/3 + 1/6 + 1/10 + 1/15 + 1/21 + 1/28 + 1/36 + 1/45 + 1/55=?
简算 12.1-(1/15+1/21)*105
裂项法,1,1\3+1\6+1\10+1\15+1\21+1\28+1\36+1\45=?2,1\3+1\15+1\35
1\3+1\6+1\10+1\15+1\21+1\28+1\36+1\45+1\55+1\66+1\78+1\91+1\
1/3+1/6+1/10+1/15+1/21+1/28+1/36+1/45这个数学题?算
1/3+1/6+1/10+1/15+1/21+1/28+1/36+1/45只要这个
小学列项法3/1+6/1+10/1+15/1+21/1+28/1+36/1+45/1
3/1+6/1+10/1+15/1+21/1+28/1+36/1+45/1等于多少?
1/3+1/6+1/10+1/15+1/21+1/28+1/36+1/45简便算法!
数列1,3,6,10,15,21,.