1-3+5-7+9-11+…+2005-2007+2009,
=2009-[(3-1)+(7-5)+(11-9)+…+(2007-2005)],
=2009-2×1004÷2,
=2009-1004,
=1005;
故答案为:1005.
1-3+5-7+9-11+…+2005-2007+2009=_.
1-3+5-7+9-11+…+2005-2007+2009=______.
数学人气:886 ℃时间:2019-12-25 10:55:49
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