Re: Statistics
\text{Given }f_{X,Y}(x,y)=2(1+x+y)^{-3}, \, x,y >0\\ \text{find the density function of }X+Y
\text{The solutions presented the method of letting }U=X+Y\text{ and }V=Y\\ \text{which resulted in }f_{U,V}(u,v)=2(1+u)^{-3}\\ \text{and then they just found the marginal density...