11 2 +21 6 +31 12 +…+91 90 +101 110
来源:学生作业帮 编辑:搜搜做题作业网作业帮 分类:数学作业 时间:2024/08/04 09:50:22
11 2 +21 6 +31 12 +…+91 90 +101 110
![11 2 +21 6 +31 12 +…+91 90 +101 110](/uploads/image/z/3510484-52-4.jpg?t=11+2+%2B21+6+%2B31+12+%2B%E2%80%A6%2B91+90+%2B101+110)
1又1/ 2 +2又1/ 6 +3又1 /12 +…+9又1/ 90 +10又1/ 110
=(1+2+3++……+9+10)+(1/2+1/6+1/12+……+1/90+1/110)
=(1+10)×10/2+(1-1/2+1/2-1/3+1/3-1/4+……+1/9-1/10+1/10-1/11)
=55+(1-1/11)
=55又10/11
=(1+2+3++……+9+10)+(1/2+1/6+1/12+……+1/90+1/110)
=(1+10)×10/2+(1-1/2+1/2-1/3+1/3-1/4+……+1/9-1/10+1/10-1/11)
=55+(1-1/11)
=55又10/11
11 2 +21 6 +31 12 +…+91 90 +101 110
1-3/2+5/6-7/12+9/20-11/30+……19/90+21/110=
5/6-7/12+9/20-11/30+……-19/90+21/110 =
计算:1/2+5/6+11/12+19/20+……+89/90+109/110=
1/2+5/6-7/12+9/20-11/30.-19/90+21/110
1-3/2+5/6-7/12+9/20-11/30+.-19/90+21/110=?
1/2=1分之2 6/7+12/13+20/21+42/43+56/57+72/73+90/91+110/111+132
111+101+91+.+41+31+21=?
4-5/6+7/12-9/20+11/30-13/42+15/56-17/72+19/90-21/90-21/110+2
(+111)+(-101)+(91)+(-81)+...+(+31)+(-21)+(+11)+(-1)怎样巧算
7/6 + 13/12 +21/20+31/30+43/42+57/56+73/72+91/90 简便计算
7/6+13/12+21/20+30/31+42/43+57/56+73/72+91/90=?