计算:m-2m-3m+4m-5m-6m+7m-8m-9m+...+2002m-2003m-2004m

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计算:m-2m-3m+4m-5m-6m+7m-8m-9m+...+2002m-2003m-2004m
计算:m-2m-3m+4m-5m-6m+7m-8m-9m+...+2002m-2003m-2004m

计算:m-2m-3m+4m-5m-6m+7m-8m-9m+...+2002m-2003m-2004m
从第一项开始,每三项为一组,m-2m-3m,4m-5m-6m,7m-8m-9m...
则它们的值分别为-4m,-7m,-10m,...-2005m.第一项与最后一项,第二项与倒数第二项,第三项与倒数第三项,...之和都为-2009m.,总共有668项.因为2004个数,每三组又为一组,所以共668项.
则总和为-2009m*(668/2)=-2009m*334.