Originally Posted by

**Greengoblin** Hi, I've been looking at surface integrals, and I'm having a problem with all the exponential functions I come across. In a single variable case:

$\displaystyle \int_{a}^b e^{2x+1} dx$

I would just take this as:

$\displaystyle \int_{a}^b e^{2x+1} dx = \int_{a}^b e^{u} du = [\frac{e^u}{f'(u)}] $

and then take the integral within the new limits given by du = 2dx.

An example of a question with exponentials in a surface integral that I'm stuck on is, evaluate:

$\displaystyle \int_{0}^2 \int_{x}^{2x} e^{x+y} dy dx$

How do I go about such a thing? I know how to do some basic surface integrals, with indicies/trig functions etc, over rectangular and non-rectangular domains BTW, but this exponential stuff has got me beat. Thanks

P.S. how can I get the brackets properly round the fraction with Latex? Thanks