1+2又1/6+3又1/13+4又1/20+5又1/30+6又1/42+7又1/56+8又1/72+9又1/90+10又1/110第二个+后是3又1/12

1+2又1/6+3又1/13+4又1/20+5又1/30+6又1/42+7又1/56+8又1/72+9又1/90+10又1/110
1+2+3+...+10=55
1/6+1/12+1/30+...+1/110=1/2-1/3+1/3-1/4+1/4-1/5...+1/10-1/110
=1/2-1/11
1+2又1/6+3又1/12+4又1/20+5又1/30+6又1/42+7又1/56+8又1/72+9又1/90+10又1/110=55+9/22

1+2又1/6+3又1/13+4又1/20+5又1/30+6又1/42+7又1/56+8又1/72+9又1/90+10又1/110
=(1+2+3+……+10)+(1/6+1/12+……+1/110)
=(1+2+……+10)+(1/2*3+1/3*4+1/4*5+……+1/10*11)
=55+[(1/2-1/3)+(1/3-1/4)+……+(1/10-1/11)]
=55+1/2-1/11
=55又9/22

=(1+2+3+…+10)+(1/6+1/12+…+1/110)
=(1+10)*11/2+(1/2*3+1/3*4+1/4*5+…1/10*11)
=55+(1/2-1/3+1/3-1/4+1/4-…+1/10-1/11)
=55+(1/2-1/11)
=55+9/22
=55又9/22