Let two-dimensional random variables (x, y) in the region D = {(x, y) x > = 0, Y > = 0, x + y

Let two-dimensional random variables (x, y) in the region D = {(x, y) x > = 0, Y > = 0, x + y

f(x,y) = 1/2, x>0, y>0, x+y