I have gotten to this point in the problem, but I am stuck with how to multiply and simplify it to get my desired answer.

3. Show that RSS can be expressed as RSS = = (I - H)E Then, show that I - H is symmetric and idempotent of rank n - p. A RSS = lly - XB/ 1 2 = ( y - XB ) ( y - XB ) = y T ( 1 - H ) y TUT-H y sub y = XB+ E = ( X B + E ) T ( 1 - H ) ( X B + E