用简便方法计算:(1)4+8+12+16+...+2008

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用简便方法计算:(1)4+8+12+16+...+2008

用简便方法计算:(1)4+8+12+16+...+2008
用简便方法计算:(1)4+8+12+16+...+2008

用简便方法计算:(1)4+8+12+16+...+2008
4+8+12+16+...+2008
= (4+2008)+(8+2004)+(12+2000)+(16+1996)+.(1004+1008)
= 2012+2012+2012+2012+ .2012
= 2012*(4+1004)/4
= 2012*1008/4
= 1006*1008/2
= (1007-1)(1007+1)/2
= (1007²-1)/2
= (1014049-1)/2
= 507024