thank you very much

[6] 4. Let y(n x 1), 1 = [1 1 1 ... 1](1 x n) and x(n x 1) be three vectors. Also let I be an n x n identity matrix. Prove n x (I - 11' )y = [(xi -x) (yi - y) i=1 where n n * = Exiln, y = [yiln. = 1 i=1 Conclude from the previous part that SST = y (1 - 1(1'1)-'1)y