贞观元年
幼苗
共回答了21个问题采纳率:100% 举报
最后一个式子缺失1/2008
设1/2002+1/2004+1/2006=x
1/2002+1/2004+1/2006+1/2008=y
(1+1/2002+1/2004+1/2006)*(1/2002+1/2004+1/2006+1/2008)-(1+1/2002+1/2004+1/2006+1/2008)* (1/2002+1/2004+1/2006)
=(1+x)y-(1+y)x
=y+xy-x-xy
=y-x
=1/2008
1年前
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