1/20+1/30+1/42+.+1/132+1/156=1-1/2-1/4-1/8-1/16-1/32-.1/1024=还有一道:2+3 1/6+5 1/12+7 1/20+11 1/30+13 1/42=还有:2/1×3×5+2/3×5×7+2/5×7×9+2/7×9×11=2/11×13+2/13×15+2/15×17+2/17×19+2/19×21=

来源:学生作业帮助网 编辑:六六作业网 时间:2024/12/24 21:21:43
1/20+1/30+1/42+.+1/132+1/156=1-1/2-1/4-1/8-1/16-1/32-.1/1024=还有一道:2+31/6+51/12+71/20+111/30+131/42=还

1/20+1/30+1/42+.+1/132+1/156=1-1/2-1/4-1/8-1/16-1/32-.1/1024=还有一道:2+3 1/6+5 1/12+7 1/20+11 1/30+13 1/42=还有:2/1×3×5+2/3×5×7+2/5×7×9+2/7×9×11=2/11×13+2/13×15+2/15×17+2/17×19+2/19×21=
1/20+1/30+1/42+.+1/132+1/156=
1-1/2-1/4-1/8-1/16-1/32-.1/1024=
还有一道:2+3 1/6+5 1/12+7 1/20+11 1/30+13 1/42=
还有:2/1×3×5+2/3×5×7+2/5×7×9+2/7×9×11=
2/11×13+2/13×15+2/15×17+2/17×19+2/19×21=

1/20+1/30+1/42+.+1/132+1/156=1-1/2-1/4-1/8-1/16-1/32-.1/1024=还有一道:2+3 1/6+5 1/12+7 1/20+11 1/30+13 1/42=还有:2/1×3×5+2/3×5×7+2/5×7×9+2/7×9×11=2/11×13+2/13×15+2/15×17+2/17×19+2/19×21=
1/20+1/30+1/42+.+1/132+1/156=1/4-1/5+1/5-1/6+1/6-1/7+...-1/12+1/12-1/13=1/4-1/13=9/52(裂项相消)
1-1/2-1/4-1/8-1/16-1/32-.1/1024=1-(1/2+1/4+1/8+1/16+...+1/1024)=1-1/2[1-(1/2)^10]/(1-1/2)=1-(1-1/1024)=1/1024
2+3 1/6+5 1/12+7 1/20+11 1/30+13 1/42=2+3+5+7+11+13+1/6+1/12+1/20+1/30+1/42=41+1/2-1/3+1/3-1/4+1/4-1/5+1/5-1/6+1/6-1/7=41+1/2-1/7=41 5/14(还是裂项相消)

第1题是365
2是1536
3是106
4是584
5是1536