1/6+1/12+1/20+1/30+.+1/2009*2010=?
问题描述:
1/6+1/12+1/20+1/30+.+1/2009*2010=?
答
1/6+1/12+1/20+1/30+.+1/2009*2010
=1/(2*3)+1/(3*4)+1/(4*5)+.+1/(2009*2010)
=(1/2-1/3)+(1/3-1/4)+.+(1/2009-1/2010)
后面的就不用说了吧.