(-1*1/2)+(-1/2*1/3)+(-1/3*1/4)+.+(-1/2008*1/2009)+(-1/2009*1/2010)+(-1/2010*1/2011)怎么写?
问题描述:
(-1*1/2)+(-1/2*1/3)+(-1/3*1/4)+.+(-1/2008*1/2009)+(-1/2009*1/2010)+(-1/2010*1/2011)怎么写?
答
(-1*1/2)+(-1/2*1/3)+(-1/3*1/4)+.+(-1/2008*1/2009)+(-1/2009*1/2010)+(-1/2010*1/2011)
=(-1+1/2)+(-1/2+1/3)+(-1/3+1/4)+.+(-1/2008+1/2009)+(-1/2009+1/2010)+(-1/2010+1/2011)
=-1+1/2011
=-2010/2011