求2/1+6/1+12/1+20/1+30/1+...110/1的和是多少
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求2/1+6/1+12/1+20/1+30/1+...110/1的和是多少
求2/1+6/1+12/1+20/1+30/1+...110/1的和是多少
求2/1+6/1+12/1+20/1+30/1+...110/1的和是多少
=1-1/2+1/2-1/3+1/3-1/4+1/5-1/6+..+1/10-1/11 =1-1/11 =10/11
2/1+6/1+12/1+20/1+30/1+...110/1 =1*2/1+2*3/1+3*4/1+...+10*11/1 =(1-2/1)+(2/1-3/1)+(3/1-4/1)+...+(10/1-11/1) =11/10