# Antidifferentiate e^r/2

1. Aug 19, 2008

### afcwestwarrior

how do i antidifferentiate that

I'm working on integration by parts problems and that little part of the problem has been bothering me, i figured that the indefinte integral would be the same but then my answer came out different

here's the whole proble, i know how to do these problems it's just that i forgot a lot of stuff about calculus and i just need to touch up on some things,

here's the problem if you want to get a clearer picture of it
∫re^r/2 dr
u=r dv =e^ r/2
du= dr v=? i just need to find v that's all

here's the formula for integration by parts just in case you forgot it
∫u dv= uv - ∫v du

2. Aug 19, 2008

### nicksauce

Re: e^r/2

So you need to evaluate $$\int e^{\frac{r}{2}}dr$$ correct?. You're aware that $$\int e^xdx = e^x$$ (plus a constant) correct? The connection between the two should be obvious... if not, make a substiution such as x=r/2.

3. Aug 19, 2008

### afcwestwarrior

Re: e^r/2

ok, i'm aware of it, so when i make the substitution for x=r/2 what's next

4. Aug 19, 2008

### nicksauce

Re: e^r/2

What's next is figuring out how dx relates to dr.

5. Aug 19, 2008

Re: e^r/2

ok i get it