(1)1+2+3+...+2010;
(2)1+(-2)+3+(-4)+...+2009+(-2010);
(1)1+2+3+...+2010;
(2)1+(-2)+3+(-4)+...+2009+(-2010);
1+2+3+…+2010 1+(-2)+3+(-4)+…+2009+(-2010)
=(1+2010)×2010÷2 =[1+(-2)]+[3+(-4)]+…+[2009+(-2010)]
=2021055 =(-1)+(-1)+…(-1)
=(-1)×(2010÷2)
= -1005
(1)1+2+3+...+2010;=(1+2010)*1005=2021055
(2)1+(-2)+3+(-4)+...+2009+(-2010);=-1*1005=-1005
1、=(1+2010)×2010/2=2021055
2、=-1-1...-1=-1×2010/2=-1005
2021055
-1005
(1)1+2+3+...+2010
=2010*(1+2010)/2
=2021055
(2)1+(-2)+3+(-4)+...+2009+(-2010)
=(-1)*2010/2
=-1005
1.1+2+3+。。。+2010
=(1+2010)+(2+2009)+。。。+(1005+1006)
=(1+2010)*1006
=2023066