第1个回答 2010-09-13
此题就是算数列An=1/n(n+1)的前六项之和
而An=(1/n)-(1/n+1)它的前n项和为Sn=n/n+1
将n=6带入得 S6=6/6+1=6/7
第2个回答 2018-12-24
1-1/2+1/2-1/3+1/3-1/4+1/4-1/5+1/5-1/6+1/6-1/7等于1-1.7/7分之六。
第3个回答 2010-09-13
1x1/2+1/2x1/3+1/3x1/4+1/4x1/5+1/5x1/6+1/6x1/7
=(1-1/2)+(1/2-1/3)+(1/3-1/4)+...+(1/6-1/7)
=1-1/7=6/7
第4个回答 2010-09-13
1x1/2+1/2x1/3+1/3x1/4+1/4x1/5+1/5x1/6+1/6x1/7
=1-1/2+1/2-1/3+1/3-1/4+1/4-1/5+1/5-1/6+1/6-1/7
=1-1/7
=6/7