The question is: "Let $X$ and $Y$ have the joint density:
\begin{equation} f(x,y)=cx(y-x)e^{-y} \tag{1} \end{equation} with $0 \leq X \leq Y \leq \infty$ 1 . Find $c$.
In order to find $c$ the density function must satisfy the condition: double integral of the joint density function equal to 1 Hence I have tried to solve this integral but i have fund that it does not converge, therefore I can't find $c$. Could anybody help me?
