hi all

Let X1 and X2 denote two independent random variables, each with a x^2(2) distribution. Find the joint p.d.f of Y1 = X1 and Y2= X2 + X1 Here note that the support of Y1, Y2 is 0<y1<y2<(infinity). Also find the marginal p.d.f of each of Y1 and Y2. Are Y1 and Y2 independent??
Hope some one can help me out