# Math Help - Determine a...

1. ## Determine a...

Hello everybody.

Given the function $p(x)=axe^{-\lambda x}(x\geq 0, \lambda \geq 0)$

Determine $a$, such that $p(x)$ would be density for $X$

2. You can integrate by part the density, but its a lot easier just making a substitution and recognizing the gamma function.
OR you can recognize the mean of an exponential and you're done.
OR recognize the gamma density.
http://en.wikipedia.org/wiki/Gamma_distribution
$\beta=\lambda$ and $\alpha=2$...

$a=\lambda^2$