Let f(x,y) = xy, where 0 x2,0 sy2, 0 x + y 2, and let it equal 0 otherwise. (a) Show that f(x,y) is a joint probability density function. (b) Find E[X]. (c) Find E[Y]. (a) Find an expression that, when solved, will show that the function is a joint density function. Select the corred answer and fill in the answer box to complete your choice. (Simplify your answer.) 2 2=x 3 OA. 2xy dxdy = OC. 00 2 2=x OB. } 3 0 - x 3 Zxy dydx = OD. 0 0 2 Xy dxdy = 0-x 3 2xy dydx =