# Homework Help: Integral Question

1. Oct 14, 2014

### mshiddensecret

1. The problem statement, all variables and given/known data

Int from 0 to 5:

te^(-e)dt

2. Relevant equations

3. The attempt at a solution

I did the integration by parts and got:

(-t)e^(-1)-e^05+e^0

I got it incorrect: "Variable 't' is not defined in this context"

2. Oct 14, 2014

### SteamKing

Staff Emeritus
Just to be clear, are you trying to evaluate:

$$\int_{0}^{5} t(e)^{-e}dt$$

because if you are, this is a very trivial integral.

3. Oct 14, 2014

### Dick

That message means that there should be no variable t in the final answer. It's a definite integral.

4. Oct 14, 2014

### Staff: Mentor

Is the above a typo?
$$\int_0^5 te^{-t}dt$$

5. Oct 14, 2014

### mshiddensecret

Yeah. That's what it looks like.

6. Oct 14, 2014

### Staff: Mentor

@mshiddensecret, try to be more careful when you post. SteamKing and Dick were unable to help you because of this mistake.

7. Oct 14, 2014

### SteamKing

Staff Emeritus
Just a suggestion: Use the Preview button to check your posts before submission. It's helped me avoid more than a few mistakes.

8. Oct 15, 2014

### Staff: Mentor

Show us the work you did in integrating by parts...

9. Oct 15, 2014

### RUber

I agree with Mark44, it seems like you went wrong somewhere in the integration by parts.
$\int_a^b u dv = \left. uv \right|_a^b - \int_a^b v du$
The first term in your answer above looks like you may have misinterpreted $\left. uv \right|_a^b$
Did you use $u = t, \, dv = e^{-t}dt$?