# Integrate by parts twice help

1. Feb 6, 2004

### Klion

I am studying for a midterm, was browsing over an old midterm and found this question

$$\int e^{3x} \cos{(x)}\; dx$$

Can't figure it out, help would be appreciated

2. Feb 6, 2004

### jamesrc

Integrate by parts twice. Post back if you get stuck.

3. Feb 6, 2004

### Klion

erm didn't think we'd gotten that far, assignment on that section isnt due until monday. No wonder I couldn't find it hehe.

O well I have 2 hrs to learn it I'm good! :)

4. Feb 6, 2004

### Klion

hmm I ended up with

$$\int e^{3x} \cos{(x)}\; dx = \frac{e^{3x}\sin{(x)} + 3e^{3x} \cos{(x})} {10}$$