1+x是整个分母吗?
x/(1+x)=(x+1-1)/(1+x)=1-1/(x+1),
设-1/(x+1)=t,
x=-(1+1/t),
x→+∞,t→0,
lim[ x→+∞]{x/(1+x)]^(x-2)}
=lim[ t→0][1+t)^(-1-1/t-2)]
lim[ t→0]1/(1+t)^(3+1/t)
=lim[ t→0]1/[(1+t)^(1/t)*(1+t)^3
=1/e.
lim[ t→0](1+t)^(1/t)=e,
lim[ t→0](1+t)^3=1,
其倒数为1/e.