(1-1/2-1/3-······-1/2006 )*(1/2+1/3+1/4·····

来源:百度知道 编辑:UC知道 时间:2024/05/15 11:01:55
(1-1/2-1/3-······-1/2006 )*(1/2+1/3+1/4·····+1/2007)-(1-1/2-1/3-……-1/2007)*(1/2+1/3+1/4+……+1/2006)
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大虾帮忙~

可以设(1/2+1/3+1/4+……+1/2006)为a
(1-1/2-1/3-······-1/2006 )为b
原式=b*(a+1/2007)-(b-1/2007)*a
=ab+b/2007-ab+a/2007
=(1-1/2-1/3-······-1/2006 )/2007+(1/2+1/3+1/4+……+1/2006)/2007
=(1-1+1/2-1/2+1/3-......1/2006+1/2007)/2007+(1-1/2+1/2-1/3+......-1/2006+1/2007)/2007
=1/2007

(1/2+1/3+1/4+……+1/2006)为a
(1-1/2-1/3-······-1/2006 )为b
原式=b*(a+1/2007)-(b-1/2007)*a
=ab+b/2007-ab+a/2007
=(1-1/2-1/3-······-1/2006 )/2007+(1/2+1/3+1/4+……+1/2006)/2007
=(1-1+1/2-1/2+1/3-......1/2006+1/2007)/2007+(1-1/2+1/2-1/3+......-1/2006+1/2007)/2007
=1/2007