-1/n(n-1)=-1/n+1/(n-1)
(-1*1/2)+(-1/2*1/3)+(-1/3*1/4)+…+(-1/2007*1/2008)=-1+1/2-1/2+1/3-1/3+1/4-......-1/2007+1/2008
=-1+1/2008=-2007/2008
察下列各式:
-1*1/2=-1+1/2,-1/2*1/3=-1/2+1/3,-1/3*1/4=-1/3+1/4
你发现的规律是-1/n(n+1)=-1/n+1/(n+1)
用规律计算:
(-1*1/2)+(-1/2*1/3)+(-1/3*1/4)+...+(-1/2009*1/2010)
=-1+1/2-1/2+1/3-1/3+1/4-……-1/2009+1/2010
=-1+1/2010
=-2009/2010
你好:
(1)你发现的规律是-1/n×1/(n+1)=-1/n+1/(n+1)
(2)用规律计算:
(-1*1/2)+(-1/2*1/3)+(-1/3*1/4)+...+(-1/2008*1/2009)
=-1+1/2-1/2+1/3-1/3+1/4-……-1/2008+1/2009
=-1+1/2009
=-2008/2009
-1/(n-1)*n
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