Can anybody try to solve and explain this problem?

X and y have a joint distribution with pdf f(x,y)=e^ -(x+y), x>0 y>0. The random variable Z is defined to be equal to U=e^ -(x+y). Find the pdf of f (u).

Answer: f(u)= -ln u for 0<u<1

Thanks

X and y have a joint distribution with pdf f(x,y)=e^ -(x+y), x>0 y>0. The random variable Z is defined to be equal to U=e^ -(x+y). Find the pdf of f (u).

Answer: f(u)= -ln u for 0<u<1

Thanks

## Comment