设bn的公差为d先根据bn=1/an+1分别有b3=1/a3+1 b3=3/4b7=a7+1 b7=2d=（b7-b3）/（7-3）=5/16b1=b3-2d=3/4-5/16=1/4bn=b1+（n-1）d=1/4+（n-1）*5/16=5n/16-1/16再根据式子bn=1/an+1,得bn=1/（5n/16-1/16）+1 化解得1...