1+2눀/2눀-1+3눀/3눀-1...+100눀/100눀-1

求答案,简单说一下思路,越快,追加分越多
2025-02-25 01:14:49
推荐回答(2个)
回答1:

解答:
裂项求和的方法
n>2时
n²/(n²-1)
=1+1/[(n-1)(n+1)]
=1+(1/2)*[1/(n-1)-1/(n+1)]
所以,
1+2²/2²-1+3²/3²-1...+100²/100²-1

=1+1+(1/2)[1/1-1/3]+1+(1/2)[1/2-1/4)]+.....+1+(1/2)[1/99-1/101]
=100+(1/2)*(1+1/2-1/100-1/101)
=100+(1/2)(3/2-201/10100)
=100+3/4-201/20200

回答2:

1