1/1*2+1/2*3+1/3*4+.+1/2011*2012
=(1-1/2)+(1/2-1/3)+(1/3-1/4)+...+(1/2011-1/2012)
=1-1/2012
=2011/2012
提问 根据式子1/N(N+1)=(N+1)-N/N(N+1)=1/N-1/(N+1),试求,1/1*2+1/2*3=1/
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