31-4/3-4/15-4/35-4/63-4/99-4/143 列项解答
发布网友
发布时间：2022-04-22 07:57
共1个回答
热心网友
时间：2024-10-21 19:39
31-4/3-4/15-4/35-4/63-4/99-4/143
=31 - 4×[1/(1×3) + 1/(3×5) + 1/(5×7) +1/(7×9) +1/(9×11) +1/(11×13)]
=31 - 2×[1 -(1/3)+(1/3)-(1/5)+(1/5)-(1/7)+(1/7)-(1/9)+(1/9)-(1/11)+(1/11)-(1/13)]
=31 - 2×[1 -(1/13)]
=31 - 2 + (2/13)
=29 + (2/13)
=29又2/13
热心网友
时间：2024-10-21 19:45
31-4/3-4/15-4/35-4/63-4/99-4/143
=31 - 4×[1/(1×3) + 1/(3×5) + 1/(5×7) +1/(7×9) +1/(9×11) +1/(11×13)]
=31 - 2×[1 -(1/3)+(1/3)-(1/5)+(1/5)-(1/7)+(1/7)-(1/9)+(1/9)-(1/11)+(1/11)-(1/13)]
=31 - 2×[1 -(1/13)]
=31 - 2 + (2/13)
=29 + (2/13)
=29又2/13
