1乘以2乘以3分之1+2乘以3乘以4分之1+……+98乘以99乘以100分之1
问题描述:
1乘以2乘以3分之1+2乘以3乘以4分之1+……+98乘以99乘以100分之1
答
裂项求和法即可:1/n*(n+1)*(n+2)=1/n[1/(n+1) -1/(n+2)]=1/n -1/(n+1)-1/2n-1/2(n+2)
1乘以2乘以3分之1+2乘以3乘以4分之1+……+98乘以99乘以100分之1
裂项求和法即可:1/n*(n+1)*(n+2)=1/n[1/(n+1) -1/(n+2)]=1/n -1/(n+1)-1/2n-1/2(n+2)