注意到极限
lim(n→∞)n*ln(1+1/n²) = lim(n→∞)n*(1/n²)= 0,
所以
lim(n→∞){[n^(n+1/n)]/[(n+1/n)^n]}
= lim(n→∞){[n^(1/n)]/[(1+1/n²)^n]}
= lim(n→∞){[n^(1/n)]/{e^[n*ln(1+1/n²)]}}
= 1≠ 0,
根据级数收敛的必要条件可知该级数发散.
注意到极限
lim(n→∞)n*ln(1+1/n²) = lim(n→∞)n*(1/n²)= 0,
所以
lim(n→∞){[n^(n+1/n)]/[(n+1/n)^n]}
= lim(n→∞){[n^(1/n)]/[(1+1/n²)^n]}
= lim(n→∞){[n^(1/n)]/{e^[n*ln(1+1/n²)]}}
= 1≠ 0,
根据级数收敛的必要条件可知该级数发散.