3,-6,9,-12…-2004,2007,-2010 求这列数的和

问题描述:

3,-6,9,-12…-2004,2007,-2010 求这列数的和

3,-6,9,-12…-2004,2007,-2010
=(3-6)+(9-12)+……+(2007-2010)
=-3×2010÷6
=-1005