计算:1/m(m+1)+1/(m+1)(m+2)+1/(m+2)(m+3)+1/(m+3)(m+4)+1/(m+4)(m+5)+.+1/(m+9)(m+10)

问题描述:

计算:1/m(m+1)+1/(m+1)(m+2)+1/(m+2)(m+3)+1/(m+3)(m+4)+1/(m+4)(m+5)+.+1/(m+9)(m+10)

1/m(m+1)=1/m-1/(m+1)
裂项法
所以原式=1/m-1/(m+1)+1/(m+1)-1/(m+2)+……+1/(m+9)-1/(m+10)
=1/m-1/(m+10)
=10/m(m+10)