Help! (Speechless)

How do I find the limits for the following:

lim x-> 0+ of e^(1/x)

Lim x->-inf of (1-e^x)/(1+e^x).

I can't figure these out...please help!

Jeannine

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- Sep 29th 2008, 08:32 AMjbecker007Limits of e functions
Help! (Speechless)

How do I find the limits for the following:

lim x-> 0+ of e^(1/x)

Lim x->-inf of (1-e^x)/(1+e^x).

I can't figure these out...please help!

Jeannine - Sep 29th 2008, 08:50 AMSoroban
Hello, Jeannine!

Here's the second one . . .

Quote:

- Sep 29th 2008, 09:15 AMjbecker007The answer in the back of my book is not -1...
It says +1.

Jeannine - Sep 29th 2008, 09:21 AMPlato
Your text is correct.

**You should know that**

Therefore you can see that - Sep 29th 2008, 10:19 AMShowcase_22
what? So was Soroban wrong? I couldn't see anything wrong with that method!

Quote:

Someone good at analysis might find a way around this though. - Sep 29th 2008, 10:25 AMJhevon
- Sep 29th 2008, 10:37 AMShowcase_22Quote:

one-sided limits don't exist if the limit is infinite. how could you approach infinity from the right? or - infinity from the left?

(I think I wrote that out correctly :s)

Then this would make:

Oops! Wrong in my previous post!

Am I making the problem too difficult?

Quote:

- Sep 29th 2008, 10:46 AMJhevon
- Sep 29th 2008, 10:58 AMbkarpuz
You may also do substitution in limit as follows:

. - Sep 29th 2008, 11:20 AMPlato
Look all of you; the discussion was about the second of the two problems not the fiist: .

That limit can easily be done by simple inspection knowing that .

The first problem was which is also easy to see that the limit does exist or is depending on the textbook.