设f(x)=1/(1+e^(1/x)) 求 lim f(x) x->0
问题描述：
设f(x)=1/(1+e^(1/x)) 求 lim f(x) x->0
答
lim(x→0-) f(x)=lim(x→0-)1/(1+e^(1/x)) =lim(t→-∞)1/(1+e^t)=lim(u→+∞)1/[1+(1/e^u)]=1lim(x→0+) f(x)=lim(x→0+)1/(1+e^(1/x)) =lim(t→+∞)1/(1+e^t)=0∵lim(x→0-) f(x)≠lim(x→0+) f(x)∴lim(x→0) f(x...