# Homework Help: Limits problem

1. Oct 19, 2011

### Saitama

1. The problem statement, all variables and given/known data
Evaluate the following limit:-
$$\lim_{x→0} \frac{e^{tan(x)}-e^x}{tan(x)-x}$$

2. Relevant equations

3. The attempt at a solution
Here are my attempts:-
I firstly apply L'Hospital rule, i get:-
$$\lim_{x→0} \frac{e^{tan(x)} \cdot sec^2(x)-e^x}{sec^2(x)}$$

If i directly substitute 0 here, i get the answer to be 0 but WolframAlpha says its 1.

I don't understand where am i wrong? :(

2. Oct 19, 2011

### Staff: Mentor

After applying L'Hopital's Rule, you're missing a term in the denominator.
$$\lim_{x→0} \frac{e^{tan(x)} \cdot sec^2(x)-e^x}{sec^2(x) - 1}$$

This is still of the indeterminate form [0/0].

3. Oct 19, 2011

### Saitama

Lol, sorry. :D

Yeah, it is still of 0/0 form but when i again apply L'Hosiptal, it is still of 0/0 form. :(

If i try to apply L'Hospital rule again and again, i am getting a 0 in denominator which will make my answer infinity, and the answer isn't that.

Is there any other method?

4. Oct 19, 2011

### Dick

The first and second derivatives the denominator are zero. The third derivative isn't.

5. Oct 19, 2011

### Saitama

Yeah it isn't.

Sorry again. I was doing some oral calculation, so i think i made a mistake. Sorry. :)

EDIT: Thanks for all the help. I have solved the problem. :)