# Math Help - double integrals with e

1. ## double integrals with e

(top = .5, bottom = 0)(top = infinity, bottom = 0) ye^(-xy) dxdy

I am not sure how to do this one

2. $\int\limits_0^\infty {ye^{ - xy} dx} = \lim _{b \to \infty } \left. { - e^{ - xy} } \right|_{x = 0}^{x = b}$

3. Originally Posted by Plato
$\int\limits_0^\infty {ye^{ - xy} dx} = \lim _{b \to \infty } \left. { - e^{ - xy} } \right|_{x = 0}^{x = b}$

Im not sure where to go to take the next integral for dy.

4. Originally Posted by plm2e
Im not sure where to go to take the next integral for dy.
Tell us. What is the value of that limit?

5. 0, i think, thats why im confused about the next step