I am trying to solve one of the questions in Rosanov - Probability (Chapter 4 Question 5), but I am not exactly sure what the question is asking of me. The question is:
Random variable $E$ with probability density:
$$p(x) = ax^2\ e^{-kx}$$
The questions are:
Find $a$;
How can I find a when there are $2$ unknowns in the equation, $k$ and $a$?
Find the distribution of $E$;
Is this an equation, and if so how do I find it?
Any help would be greatly appreciated.