1+2/1+6/1+12/1+20/1+30/1+42/1......+90/1=?
来源:百度知道 编辑:UC知道 时间:2024/05/29 00:14:54
拜托帮帮我!
1+2/1+6/1+12/1+20/1+30/1+42/1......+90/1
=1+1*2/1+2*3/1+3*4/1+……+9*10/1
=1+(1/1-2/1)+(2/1-3/1)+……+(9/1-10/1)
=1+1-10/1
=10/19即十分之十九
你写错了吧
应该是
1 + 1/2 + 1/6 + …… + 1/90
=1 + 1/1*2 + 1/2*3 + …… + 1/9*10
=1 + ( 1 - 1/2 ) + ( 1/2 - 1/3 )+ …… + ( 1/9 - 1/10 )
=1 + 1 - 1/10
=19/10
1+1-1/2+1/2-1/3+1/3-1/4.....+1/9-1/10=2-1/10=19/10
9/10
331
1/2+1/6+1/12+1/20+1/30
-1/2-1/6-1/12-1/20-``````````````-1/4026042
1/2+1/6+1/12+......+1/1980+1/2070=?
1/2+1/6+1/12+1/20+1/30+1/42+1/56+1/72+1/90=
1/2+1/6+1/12+1/20+1/30+1/42+1/56+1/72+1/90=?
计算1/2 +1/6+1/12+1/20+1/30+1/42=
求解1/2-1/6-1/12-1/20-1/30-1/42
1/2+1/6+1/12+1/20+1/30......1/9900
找规律:1/2 1/6 1/12 1/20 ......
1/2,1/6,1/12,1/30,?