**PLEASE SHOW ALL WORK AND STEPS**
 
 Let f(y1,y2) = 2(1 - y1) be a joint density of Y1 and Y2- Our bounds are 0 GE y1 GE 1 and 0 GE ya GE 1  What are the marginal densities of Y1 and Y2?  Are Y1 and Y2 independent?  Find the conditional density fy1|y2 = y2(y1).  Find the joint density of U_1, U_2 where U_1 = Y1 and U_2 = Y1,Y2.