Thursday, 15 October 2015

calculus - indeterminate limit where applying L'Hopitals Rules directly doesn't help and using ln gives wrong answer

I am trying to determine the limit limx0e1/xx. Plugging in x directly, yields 0/0 which is indeterminate. Applying L'Hopitals rule does not simplify the fraction, in fact the result is even more complicated and looks like a dead end, i.e. limx0e1/xx=limx0e1/xx2.
So I tried taking the natural log, i.e.
y=limx0e1/xx



ln(y)=limx0ln(e1/xx)=limx0[1/xln(x)]=limx01xln(x)x



Applying L'Hopitals Rule here gives me
limx01ln(x)=+ which is wrong; it should be .




I think I am making a very simple mistake but I don't see it.



Can anyone help?

No comments:

Post a Comment

real analysis - How to find limhrightarrow0fracsin(ha)h

How to find limh0sin(ha)h without lhopital rule? I know when I use lhopital I easy get $$ \lim_{h\rightarrow 0}...