2004*2003-2002*2001+2000*1999-1998*1997+……+4*3-2*1
=(2004*2003-2002*2001)+(2000*1999-1998*1997)+……+(4*3-2*1)
=(2004+2003+2002+2001)+(2000+1999+1998+1997)+……+(4+3+2+1)
=(2004+1)×2004/2
=2005×1002
=20090102004*2003-2002*2001=2004+2003+2002+2001是怎么推出来的?2004*2003-2002*2001==2004+2004×2002-2002*2001=2004+2002*(2004-2001)=2004+2002*3=2004+2003+2002+2001
2004*2003-2002*2001+2000*1999-1998*1997+……+4*3-2*1=
2004*2003-2002*2001+2000*1999-1998*1997+……+4*3-2*1=
数学人气:531 ℃时间:2019-12-16 19:26:06
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