1/1987*1988+1/1988*1989+1/1989*1990+……+1/1996*1997+1/1997*1998+1/1998*1999+1/1999=?
来源:学生作业帮助网 编辑:作业帮 时间:2024/07/14 22:48:53
![1/1987*1988+1/1988*1989+1/1989*1990+……+1/1996*1997+1/1997*1998+1/1998*1999+1/1999=?](/uploads/image/z/606819-3-9.jpg?t=1%2F1987%2A1988%2B1%2F1988%2A1989%2B1%2F1989%2A1990%2B%E2%80%A6%E2%80%A6%2B1%2F1996%2A1997%2B1%2F1997%2A1998%2B1%2F1998%2A1999%2B1%2F1999%3D%3F)
x)370`m a[ٖڏX$daYBYYBYZ$l;ںi{m!VBLZ,
FA0FA
Qx鄾s=uϺ~O~qAb_ \m
1/1987*1988+1/1988*1989+1/1989*1990+……+1/1996*1997+1/1997*1998+1/1998*1999+1/1999=?
1/1987*1988+1/1988*1989+1/1989*1990+……+1/1996*1997+1/1997*1998+1/1998*1999+1/1999=?
1/1987*1988+1/1988*1989+1/1989*1990+……+1/1996*1997+1/1997*1998+1/1998*1999+1/1999=?
原式=1/1987-1/1988+1/1988-1/1989+1/1989-1/1990.+1/1998-1/1999+1/1999
=1/1987 (后面的全部抵销)