、设xn=[n!^(1/n)]/n,则
㏑xn=㏑{[n!^(1/n)]/n}
=(1/n)㏑[n!/n^n]
=(1/n)[㏑1/n+㏑2/n+…+㏑n/n]
=(1/n)∑(k=1,n)㏑k/n(可以理解为积分和)
2、转化为定积分:
=∫(0,1)lnxdx
=[xlnx-x](0,1)
3、求无穷积分值:
=-1-lim(x→0)[xlnx-x]
=-1-lim(x→0)lnx/(1/x)
=-1-lim(x→0)(1/x)/(-1/x^2)
=-1-lim(x→0)(-x)
=-1;
所以:lim(n→∞)㏑xn=-1
lim(n→∞)xn=1/e.