1/1*2=1-1/2
1/2*3=1/2-1/3
1/3*4=1/3-1/桐念4
……
依此类局稿困推,最后相加得敬缺
1-1/15=14/15
1/1*2+1/2*3+1/3*4+1/4*5+1/镇肢5*6+1/6*7+1/7*8+1/8*9+1/9*10+1/10*11+1/11*12+1/12*13+1/13*14+1/14*15
=(1/1-1/2)+(1/2-1/3)+……+(1/14-1/15)
=1/1-1/猛旅帆2+1/枝雹2-1/3+……+1/14-1/15
=1-1/15
=14/15
14/15
???1/1*2
2乘的是分母还是1/1??
要都是乘以分母的枝腊话庆物就是14/15
要是乘以前面的分式那就是。。。。誉搭液就是LZ你变态!!!
1/N(N+1)=1/N-1/迅兄洞(N+1)
1/1*2+1/2*3+1/3*4+1/4*5+1/5*6+1/6*7+1/7*8+1/8*9+1/9*10+1/10*11+1/11*12+1/12*13+1/13*14+1/14*15
=1-1/2+1/亩枯2-1/3+1/3-1/4+......+1/14-1/15
=1-1/15=14/15懂尘闹了吗?