1-2+3-4+5-6+7-8……+4999-5000=?

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1-2+3-4+5-6+7-8……+4999-5000=?1-2+3-4+5-6+7-8……+4999-5000=?1-2+3-4+5-6+7-8……+4999-5000=?1-2+3-4+5-6+7

1-2+3-4+5-6+7-8……+4999-5000=?
1-2+3-4+5-6+7-8……+4999-5000=?

1-2+3-4+5-6+7-8……+4999-5000=?
1-2+3-4+5-6+7-8……+4999-5000
=(1-2)+(3-4)+(5-6)+(7-8)+.+(4999-5000)
=(-1)+(-1)+(-1)+(-1)+.+(-1)
=(-1)*2500
=-2500

5000/2X(-1)= -2500
因为是两个两个组合为-1

=-1-1-1-1-1-...-1
=-2005

(1-2)+(3-4)+(5-6)+(7-8)……+(4999-5000)=-1-1-1-1-1-1.....-1-1=-2500

-2500 !!!!

一共5000项,每2项一合并是(-1)*2500=-2500

-2500

-2+3-4+5-6+7-8……+4999-5000
=(1-2)+(3-4)+(5-6)+(7-8)+.....+(4999-5000)
=(-1)+(-1)+(-1)+(-1)+......+(-1)
=(-1)*2500
=-2500

原式=(1+3+5+…+4999)-(2+4+6+…+5000)
=(1+4999)[(4999-1)/2+1]/2 -(2+5000)[(5000-2)/2+1]/2
= 6250000-6252500
=-2500

-2500