解法1:
ln [(1+ 1/x)^x]=x* ln (1+ 1/x)=ln (1+ 1/x) /(1/x).
由洛必达法则,
lim(x趋于零)[ln (1+ 1/x) /(1/x)]
=lim(x趋于零){ [1/(1+ 1/x)*(-1 /x^2)] /(-1 /x^2) }
=lim(x趋于零)[1/(1+ 1/x)]
=0.
所以 lim(x趋于零)[(1+ 1/x)^x]=e^0=1.
解法2:
ln [(1+ 1/x)^x]=x* ln (1+ 1/x)=ln (1+ 1/x) /(1/x).
令 y=1/x,则当x趋于零时,y趋于无穷大.
由洛必达法则,
lim(x趋于零)[ln (1+ 1/x) /(1/x)]
=lim(y趋于无穷大)[ln(1+y)/y]
=lim(y趋于无穷大){[1/(1+y)] /1}
=0.
所以 lim(x趋于零)[(1+ 1/x)^x]=e^0=1.