1-2/1(1+2)-3/(1+2)(1+2+3)-4/(1+2+3)(1+2+3+4)-……-20/(1+2+3+……+19)(1+2+3+……+20)=?

来源：学生作业帮助网编辑：六六作业网时间：2024/12/31 19:58:54

1-2/1*(1+2)-3/(1+2)*(1+2+3)-4/(1+2+3)*(1+2+3+4)-……-20/(1+2+3+……+19)*(1+2+3+……+20)=?1-2/1*(1+2)-3/(1+

1-2/1*(1+2)-3/(1+2)*(1+2+3)-4/(1+2+3)*(1+2+3+4)-……-20/(1+2+3+……+19)*(1+2+3+……+20)=?
1-2/1*(1+2)-3/(1+2)*(1+2+3)-4/(1+2+3)*(1+2+3+4)-……-20/(1+2+3+……+19)*(1+2+3+……+20)=?

1-2/1*(1+2)-3/(1+2)*(1+2+3)-4/(1+2+3)*(1+2+3+4)-……-20/(1+2+3+……+19)*(1+2+3+……+20)=?
通项为-2/(n-1)+4/n+2/(n+1)
所得结果为1/210