# Homework Help: Integral Problem

1. Oct 5, 2009

### Void123

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

integral[x*exp(iax + b)] dx

2. Relevant equations

3. The attempt at a solution

I know there is a an integral for this I can pull out from a table, but is there any direct analytical way to solve it? Perhaps by parts?

Thanks.

2. Oct 5, 2009

### jbunniii

You can use

$$e^{iax + b} = e^{iax} e^b$$

to simplify the integrand. Yes, integration by parts looks promising.

3. Oct 6, 2009

### Void123

What if I had $$\int^{\infty}_{-\infty}x exp(-ax^{2})exp(bx) dx$$

4. Oct 6, 2009

### lanedance

haven't tried it... but how about combining the exponetial terms, then complete the square in the exponential, substitute for y = x+c in the square, then use another substitution u = y^2

the only problem i can see is in you integration limits... may have to have a think about those & maybe split the integral