干LZ
幼苗
共回答了20个问题 举报
1-1/2+1/3-1/4+.....+1/2011-1/2012
=(1+1/3+1/5+....+1/2011)-(1/2+1/4+....+1/2012)
=(1+1/3+1/5+.....+1/2011+1/2+1/4+.....+1/2012)-(1/2+1/2+1/4+1/4+.....+1/2012+1/2012)
=(1+1/2+1/3+1/4+.....+1/2011+1/2012)-(1+1/2+1/3+....+1/1006)
=1/1007+1/1008+1/1009+....+1/2011+1/2012
1年前
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