8-5=3.101-98=3 每项分母乘积的后项减前项均为3∴ 1\5*8+…+1\98*101=1/3[1/5-1/8]+1/3[1/8-1/11]+.+1/3[1/98-1/101]=1/3{1/5-1/8+1/8-1/11+1/11-1/14+1/14-1/17+.+1/98-1/101} 中间均相抵消=1/3{1/5-1/101}=1/3X{96...