# Math Help - marginal p.d.f

1. ## marginal p.d.f

given a complicated p.d.f of x,y. How do you find the p.d.f of X?
i.e.
kx^(2)e^(-ax)e^(-xy) x>0 & y>0

2. The marginal distribution of one of the random variables is obtained by integrating the joint pdf with respect to the other variable

$\displaystyle f_{X}(x) = \int_Y f(x,y)\;dy\;=\; .....$