How to Integrate by Parts Twice for e^3x cos(x)?

[Klion]

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


<br /> \int e^{3x} \cos{(x)}\; dx <br />

Can't figure it out, help would be appreciated

 

[jamesrc]

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

 

[Klion]

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

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

 

[Klion]

hmm I ended up with

<br /> \int e^{3x} \cos{(x)}\; dx = \frac{e^{3x}\sin{(x)} + 3e^{3x} \cos{(x})} {10}<br />

that sound about right?

 

[jamesrc]

Looks good to me.