The joint pdf of X, Y, and Z is given by
$f(x,y,z) = 8xy\,\mathsf e^{-z}$ for $0≤x<y≤1, z>0$ (0 otherwise)
What is the joint pdf of $U=X/Y$ and $V = Y$?
My idea is that we should create another dummy variable for $Z$ and then use the Jacobian for 3x3 matrices. Is this correct or do I have another alternative?