find the joint distribution of

$\displaystyle f(x,y) = \left\{ \begin{array}{rcl} 4xy & \mbox{for} & 0 \leq x \leq 1, 0 \leq y \leq 1 \\

0 \ \ \mbox{elsewhere}

\end{array}\right.$

considering the fact that it's continuous, you can't have a table with infinitively values, so do you just omit the table and approach it another way?