2/1+6/1+12/1+...+110/1 21/2+77/2+165/2+...+1677/2+2021/2

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2/1+6/1+12/1+...+110/1 21/2+77/2+165/2+...+1677/2+2021/2
2/1+6/1+12/1+...+110/1 21/2+77/2+165/2+...+1677/2+2021/2

2/1+6/1+12/1+...+110/1 21/2+77/2+165/2+...+1677/2+2021/2
题目应该是分子分母都倒过来写了.
(1)原式=1/1*2+1/2*3+1/3*4+.+1/10*11
=(1/1-1/2)+(1/2-1/3)+(1/3-1/4).+(1/10-1/11)
=1-1/11=10/11
(2)原式=2/3*7+2/7*11+……+2/39*43+2/43*47
=(1/2)*(1/3-1/7)+(1/2)*(1/7-1/11)+……+(1/2)*(1/39-1/43)+(1/2)*(1/43-1/47)
=(1/2)*(1/3-1/7+1/7-1/11+……+1/39-1/43+1/43-1/47)
=(1/2)*(1/3-1/47)
=(1/2)*44/141=22/141

2/1+6/1+12/1+...+110/1
=(1*2)/1+(2*3)/1+...+(10*11)/1
=1-2/1+2/1-3/1+...+10/1-11/1
=1-11/1
=11/10
21/2+77/2+165/2+...+1677/2+2021/2
=2*[(3*7)/1+(7*11)/1+...+(39*43)/1+(43*47)/1...

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2/1+6/1+12/1+...+110/1
=(1*2)/1+(2*3)/1+...+(10*11)/1
=1-2/1+2/1-3/1+...+10/1-11/1
=1-11/1
=11/10
21/2+77/2+165/2+...+1677/2+2021/2
=2*[(3*7)/1+(7*11)/1+...+(39*43)/1+(43*47)/1]
=2*[(3/1-7/1)*4/1+(7/1-11/1)*4/1+...+(43/1-47/1)*4/1]
=2*4/1*(3/1-7/1+7/1-11/1+...+43/1-47/1)
=2/1*(3/1-47/1)
=2/1*141/44
=141/22
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2/1+6/1+12/1+...+110/1
=1-2/1+2/1-3/1+3/1-4/1+...+10/1-11/1
=1-11/1
=11/10
21/2+77/2+165/2+...+1677/2+2021/2
=2*(3*7/1+7*11/1+11*15/1+....+39*43/1+43*47/1)
=2*(4/1)*(3/1-7/1+7/1-11/1+11/1-15/1+.....+39/1-43/1+43/1-47/1)
=(2/1)*(3/1-47/1)
=(2/1)*(141/44)
=141/22

1/2-1/6-1/12-1/20-...-1/110 1/2+1/6+1/12+……+1/110 (1-1/2)+(1-1/6)+(1-1/12)+...+(1-1/110)=? 2/1+6/1+12/1+20/1+30/1+...+110/1=多少. 1/2+1/6+1/12+1/20+1/30+.+1/110=? 求1/2+1/6+1/12+20/1+30/1+...1/110 2/1+6/1+12/1+...90/1+110/1+132/1的值是多少? 1/2+1/6+1/12+…+1/90+1/110+1/132 求2/1+6/1+12/1+20/1+30/1+...110/1的和是多少 1/2+1/6+1/12+...1/90+1/110+1/132 1/2+1/6+1/12+.1/90+1/110+1/132=? 1/2+1/6+1/12+1/20+1/30+1/42+1/56+1/72+1/90+1/110 1/2+1/6+1/12+1/20+.1/110=? 帮忙想个题：简算：1/2+1/6+1/12+1/20+.+1/110=? 六年级算术题(直接写得数)1/2+1/6+1/12+1/20+.+1/110 计算：1/2+5/6+11/12+...109/110 1/2+5/6+11/12+.+109/110 1/2+5/6+11/12+ 109/110=?