(1+1/2+ +1/2007)x(1/2+1/3+ +1/2008)-(1+1/2+ +1/2008)x(1/2+1/3+ +1/2007)=?

问题描述:

(1+1/2+ +1/2007)x(1/2+1/3+ +1/2008)-(1+1/2+ +1/2008)x(1/2+1/3+ +1/2007)=?

=(1+1/2+ +1/2007)x1/2008-(1/2+1/3+ +1/2007)x1/2008
=(1+1/2+ +1/2007-1/2-1/3- -1/2007)x1/2008
=1x1/2008
=1/2008