一道数学问题~要列式啊!!
简便算法~<(1+1/1999)+(1/2000)+(1/2001)>*<(1/1999)+(1/2000)+(1/2001)+(1/2002)>-<(1+1/1999)+(1/2000)+(1/2001)+(1/2002)>*<(1/1999)+(1/2000)+(1/2001)>最后追加悬赏~
参考答案:设A=<(1/1999)+(1/2000)+(1/2001)>
原式=(1+A)*(A+1/2002)-(1+A+1/2002)*A
=A+A*A+1/2002+A/2002-A-A*A-A/2002
=1/2002