# Homework Help: A quick integration prob.

1. May 27, 2007

### Triggy

How do you integrate $$\int secx^{3}tanxdx$$

I'm substituting $$u = tanx$$ so $$du = sec^2xdx$$

Now the problem is when I made sec^3x in to sec^2xsecx then I had a secx left over after my substitution. What do I do with this?

PS: Sorry I'm new at latex and I dont know how to get rid of that {

Last edited: May 27, 2007
2. May 27, 2007

### Kurdt

Staff Emeritus
Try sec(x) = u and substituting. When you differentiate this it may become clearer.

3. May 27, 2007

### Triggy

Aahh! Thanks tending to infinity man. I got it.

[tex]\{1/3sec^3x} [\tex]

4. May 27, 2007

### Triggy

Is there like a post on how to use latex?

5. May 27, 2007

### Kurdt

Staff Emeritus
If you click on latex images it shows you the code and there is a link below the code to a short PDF with a few tips and small tutorial.

https://www.physicsforums.com/misc/howtolatex.pdf

6. May 27, 2007

### George Jones

Staff Emeritus
Delete the \{ and the }.

7. May 27, 2007

### Triggy

Awsome. Thanks Kurdt and GJ