n趋向正无穷 求极限n*[e^2-(1+1⼀n)^2n]

答案是e^2,可是没有过程啊,哪位数学达人帮帮忙,感谢了!
2025-05-21 01:31:20
推荐回答(1个)
回答(1):

n*[e^2-(1+1/n)^2n]
=n*(1+1/n)^2n*[e^2/(1+1/n)^2n-1]
~e^2*n*ln[e^2/(1+1/n)^2n]
(等价无穷小因子替换)
=e^2*n*[2-2n*ln(1+1/n)]
=e^2*[2/n-2*ln(1+1/n)]/(1/n^2)
再转化成连续函数求极限:

x(x趋于0+

~
1/n(n趋于正无穷)
lim
e^2*[2x-2*ln(1+x)]/x^2
用一次罗比达结果为e^2
则原极限=e^2