第1个回答 2011-10-22
1/3*5+1/5*7+1/7*9+...+1/1999*2001
=1/2*(1/3-1/5)+1/2*(1/5-1/7)+1/2*(1/7-1/9)+...+1/2*(1/1999-1/2001)
=1/2*(1/3-1/5+1/5-1/7+1/7-1/9+...+1/1999-1/2001)
=1/2*(1/3-1/2001)
=1/2*666/2001
=333/2001
=111/667
=1/2*(1/3-1/5)+1/2*(1/5-1/7)+1/2*(1/7-1/9)+...+1/2*(1/1999-1/2001)
=1/2*(1/3-1/5+1/5-1/7+1/7-1/9+...+1/1999-1/2001)
=1/2*(1/3-1/2001)
=1/2*666/2001
=333/2001
=111/667
第2个回答 2011-10-22
解：1/3*5+1/5*7+1/7*9+...+1/1999*2001
=1/2(1/3-1/5+1/5-1/7+..+1/1999-1/2001)
=1/2(1/3-1/2001)
=1/2(2001-3)/6003
=999/6003
=111/667本回答被提问者采纳
=1/2(1/3-1/5+1/5-1/7+..+1/1999-1/2001)
=1/2(1/3-1/2001)
=1/2(2001-3)/6003
=999/6003
=111/667本回答被提问者采纳
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