# Homework Help: Another double integral question

1. Jul 12, 2008

### math_04

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

Given the integral (shown in attachment) make a clear sketch of the region of integration and express the integral with the order of integration reversed. Evaluate the integral you found in (ii).

2. Relevant equations

3. The attempt at a solution

Everything is in the attachment. I kinda got lost in evaluating the integral. Please check whether everything else is right and hopefully im on the right track!

#### Attached Files:

• ###### Math015.jpg
File size:
31.9 KB
Views:
94
2. Jul 13, 2008

### math_04

wow, takes a while to approve attachments.

3. Jul 13, 2008

### rocomath

If you have Firefox, install the Add-on "Imagebot" and it's easier than pie!

4. Jul 13, 2008

### math_04

cmon, approve the image lol. i dont use firefox.

5. Jul 13, 2008

### math_04

whats happened with my attachment? Why is it taking so long

6. Jul 13, 2008

### rocomath

Maybe bc most of the Mods were sleeping??? Every person that helps here volunteers, relax you're not special.

7. Jul 13, 2008

### Defennder

There's an error in this step:
$$-\frac{1}{2}4x^3(x^4+y^2)^{-3/2}$$ is not the same as $$\frac{-2x^3}{\sqrt{x^4+y^2}}$$

That's about all I can decipher from your working. The limits appear to be correct in the new order of integration. If you're doing integration by parts, you didn't include the expression for dv and v.

8. Jul 13, 2008

### math_04

Cheers mate, finally got the answer. i made a mistake with my substitution.