作业帮1/2+1/6+1/12+1/20+1/30+1/42+1/56=
来源：学生作业帮助网 编辑：作业帮 时间：2024/04/28 22:52:11
1/2+1/6+1/12+1/20+1/30+1/42+1/56=
1/2+1/6+1/12+1/20+1/30+1/42+1/56=
1/2+1/6+1/12+1/20+1/30+1/42+1/56=
1/2+1/6+1/12+1/20+1/30+1/42+1/56
=1/(1*2)+1/(2*3)+1/(3*4)+1/(4*5)+1/(5*6)+1/(6*7)+1/(7*8)
=1-1/2+1/2-1/3+1/3-1/4+1/4-1/5+1/5-1/6+1/6-1/7+1/7-1/8
=1-1/8
=7/8
原式=1-1/2+1/2-1/3……+1/7-1/8
=7/8
7/8
1／2＋1／2－1／3＋1／3－1／4．．．．＋1／7－1／8＝7／8