计算题：-1/2+1/6+1/12+1/20+1/30+1/42
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计算题：-1/2+1/6+1/12+1/20+1/30+1/42计算题：-1/2+1/6+1/12+1/20+1/30+1/42计算题：-1/2+1/6+1/12+1/20+1/30+1/42-1/2
计算题：-1/2+1/6+1/12+1/20+1/30+1/42
计算题：-1/2+1/6+1/12+1/20+1/30+1/42
计算题：-1/2+1/6+1/12+1/20+1/30+1/42
-1/2+1/6+1/12+1/20+1/30+1/42
=-1/2+1/2*3+1/3*4+1/4*5+1/5*6+1/6*7
=-1/2+1/2-1/3+1/3-1/4+1/4-1/5+1/5-1/6+1/6-1/7
=-1/7
-1/7
原式=-1/2+(1/2-1/3)+(1/3-1/4)+(1/4-1/5)+(1/5-1/6)+(1/6-1/7)
=-1/2+1/2-1/3+1/3-1/4+1/4-1/5+1/5-1/6+1/6-1/7
=-1/7
58/84