# Integral of e^x/x

1. Jul 1, 2010

### 3.1415926535

First of all, I want to clarify that i know the answer is Ei(x). I have found a way to calculate this integral but the result is definetely wrong Anyway, have a look and tell me where is my mistake

Last edited by a moderator: May 4, 2017
2. Jul 1, 2010

### HallsofIvy

Many people (and I am one when I am not using my home computer where I know how strong my virus- protection is) will not open "word" files. They are notorious for harboring viruses.

3. Jul 1, 2010

### 3.1415926535

Really ? Didn't know that... Well, i can garentee it contains only calculus. Apart from that why why would someone upload a doc file with viruses to physics forums?? I hope i learn "latex" soon so i won't need these word documents

4. Jul 1, 2010

### Staff: Mentor

For at least two reasons: they knew that the file contained a virus and wanted to spread it; they didn't know the file contained a virus. For a person intent on spreading a computer virus, there is nothing sacrosanct about physicsforums.

5. Jul 1, 2010

6. Jul 1, 2010

### n.karthick

It seems that you have missed 1/x in step 2. The final answer you got is just e^x +
c. How it can be? Can you check step no. 2?

Regarding MS word one can disable macros and defend from viruses. For me it worked!!

7. Jul 2, 2010

### 3.1415926535

Here is the google docs equation

Last edited by a moderator: May 4, 2017
8. Jul 2, 2010

### 3.1415926535

I know it can't be e^x+c ... I didn't miss it!! Check the google document du=1/x dx

9. Jul 2, 2010

### n.karthick

e^lnx = x is true only if x>0 right? I tried conventional method to solve this integral and i got different answer. I have to check my answer.

Last edited: Jul 2, 2010
10. Jul 2, 2010

### losiu99

It's the 5th line. $$u$$ is independent variable here, so $$u'=1$$.

11. Jul 2, 2010

### n.karthick

12. Jul 2, 2010

### 3.1415926535

Of course. There can't be a ln(-|x|)

13. Jul 2, 2010

### 3.1415926535

Really? I thought that since u=g(x) u'=g'(x)=lnx'=1/x

14. Jul 2, 2010

### The Chaz

Gave you WHAT answer? That article doesn't explain where the error is...

Yes, you are having problems with the chain rule. If v = e^u, then dv/du = e^u, and dv = (e^u)du, which doesn't help solve the integral.
If you wanted to take dv/dx, then that would equal (dv/du)*(du/dx), but that's not what you're doing... (and won't help any)

15. Jul 3, 2010

### tony.c.tan

Try this one:
$$e^x\sum_{i=1}^\infty(i-1)!x^{-i}$$

16. Jul 3, 2010

### Anonymous217

$$e^{elnx} = e^x$$ ?