同分子分数的简算答得好,实用,简便,还加悬赏用文字 - 知识问答

同分子分数的简算答得好,实用,简便,还加悬赏用文字表达

1个回答

2+2/2*3+2/3*4+2/4*5+2/5*6+2/6*7+.+2/2011*2012
=2*(1+1/2*3+1/3*4+1/4*5+1/5*6+.1/2011*2012)
=2*(1-1/2+1/2-1/3+1/3-1/4+1/4-1/5+1/5-.-1/2011+1/2011-1/2012)
=2*(1-1/2012)
=2*2011/2012
=2011/1006

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