=1-1/2+1-1/2+1/3+1-1/3+1/4.........+1-1/6+1/7=6-1+1/7=36/7若有问题,请追问,没有问题,请给个五颗星的采纳,谢谢
解:
原式=(1-1/2)+(1-1/6)+(1-1/12)+(1-1/20)+(1-1/30)+(1-1/42)
=6×1-【1/2+1/6+1/12+1/20+1/30+1/42】
=6-【(1-1/2)+(1/2-1/3)+(1/3-1/4)+(1/4-1/5)+(1/5-1/6)+(1/6-1/7)】
=6-【1-1/2+1/2-1/3+1/3-1/4+1/4-1/5+1/5-1/6+1/6-1/7】
=6-【1-1/7】
=6-6/7
=36/7