bjs61
春芽
共回答了20个问题采纳率:90% 举报
3/2+7/6+13/12+21/20+31/30+43/42+57/56 =1+1/2+1+1/6+1+1/12+1+1/20+1+1/30+1+1/42+1+1/56 =7+1/(1*2)+1/(2*3)+1/(3*4)+1/(4*5)+1/(6*7)+1/(7*8) =7+(1-1/2)+(1/2-1/3)+(1/3-1/4)+(1/4-1/5)+(1/5-1/6)+(1/6-1/7)+(1/7-1/8) =7+1-1/8 =7+7/8 =7*9/8 =63/8
1年前
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