ainana001
幼苗
共回答了15个问题采纳率:66.7% 举报
6-3/2-7/6-13/12-21/20-31/30
=6-(1+1/2)-(1+1/6)-(1+1/12)-(1+1/20)-(1+1/30)
=6-1-1/2-1-1/6-1-1/12-1-1/20-1-1/30
=-(1/2+1/6+1/12+1/20+1/30)
=-[(1-1/2)+(1/2-1/3)+(1/3-1/4)+(1/4-1/5)+(1/5-1/6)]
=-[1-1/2+1/2-1/3+1/3-1/4+1/4-1/5+1/5-1/6]
=-[1-1/6]
=-5/6
1年前
1