Question

答案中的左右极限(横线那行)是如何求得的.

Answer 1

x->0- 时,1/x -> -∞,则e^(1/x) -> e^(-∞)=0,此时极限值f(0-)=(0-1)/(0+1)=-1

x->0+ 时,1/x -> +∞,则e^(1/x) -> e^(+∞)=+∞,此时极限值f(0+)=(+∞-1)/(+∞+1)=(+∞)/(+∞)=1